As I understand it, most ATX style PC setups have a fan above the CPU
that blows air down onto the CPU to keep it cool, and the hot air
bounces around inside the PC case until it can find an exit (if it's lucky).
As I see it, there are two problems with this,
a) unless you have a vent in the side of the PC case, the air being
taken in by the CPU cooler will not be cool, because it's air from
inside the PC case?
b) the hot air from the bottom of the heat sink ends up warming up the
Motherboard?
I was looking at the Dell CPU coolers of the GX280, GX620 workstaions
(Intel P4 / Pentium D) and the PE2400, PE 2600, PE2800 servers (Intel
Xeon). The design is completely different. The air is sucked in from the
front of the case, straight over the CPU and out of the back - how cool
is that? Pretty cool, and there's hardly any noise either.
> As I understand it, most ATX style PC setups have a fan above the CPU that blows air down onto the
> CPU to keep it cool, and the hot air
> bounces around inside the PC case until it can find an exit (if it's lucky).
No luck involved, there is normally at least the power supply
fan than moves the air inside the case to outside the case.
> As I see it, there are two problems with this,
> a) unless you have a vent in the side of the PC case, the air being taken in by the CPU cooler
> will not be cool, because it's air from inside the PC case?
Quite a few of the later cases have a duct
that supplys outside air to the cpu and fan.
> b) the hot air from the bottom of the heat sink ends up warming up the Motherboard?
In practice that really doesnt produce much of a problem.
> I was looking at the Dell CPU coolers of the GX280, GX620 workstaions
> (Intel P4 / Pentium D) and the PE2400, PE 2600, PE2800 servers (Intel
> Xeon). The design is completely different. The air is sucked in from
> the front of the case, straight over the CPU and out of the back -
> how cool is that? Pretty cool, and there's hardly any noise either.
the dell solution is the BX rather than the ATX cooling
-john
"Rod Speed" <rod.speed.aaa@gmail.com> wrote in message
news:4nlqi5Fb4b32U1@individual.net...
> Gerry_uk <gerry666uk@yahoo.com> wrote
>
>> As I understand it, most ATX style PC setups have a fan above the CPU
>> that blows air down onto the CPU to keep it cool, and the hot air
>> bounces around inside the PC case until it can find an exit (if it's
>> lucky).
>
> No luck involved, there is normally at least the power supply
> fan than moves the air inside the case to outside the case.
>
>> As I see it, there are two problems with this,
>
>> a) unless you have a vent in the side of the PC case, the air being taken
>> in by the CPU cooler will not be cool, because it's air from inside the
>> PC case?
>
> Quite a few of the later cases have a duct
> that supplys outside air to the cpu and fan.
>
>> b) the hot air from the bottom of the heat sink ends up warming up the
>> Motherboard?
>
> In practice that really doesnt produce much of a problem.
>
>> I was looking at the Dell CPU coolers of the GX280, GX620 workstaions
>> (Intel P4 / Pentium D) and the PE2400, PE 2600, PE2800 servers (Intel
>> Xeon). The design is completely different. The air is sucked in from
>> the front of the case, straight over the CPU and out of the back -
>> how cool is that? Pretty cool, and there's hardly any noise either.
>
> Its just one way of doing things.
>
"Gerry_uk" <gerry666uk@yahoo.com> wrote in message
news:1159049196.61449.0@demeter.uk.clara.net...
> Hi,
>
> As I understand it, most ATX style PC setups have a fan above the CPU
> that blows air down onto the CPU to keep it cool, and the hot air
> bounces around inside the PC case until it can find an exit (if it's
lucky).
>
> As I see it, there are two problems with this,
>
> a) unless you have a vent in the side of the PC case, the air being
> taken in by the CPU cooler will not be cool, because it's air from
> inside the PC case?
>
> b) the hot air from the bottom of the heat sink ends up warming up the
> Motherboard?
>
> I was looking at the Dell CPU coolers of the GX280, GX620 workstaions
> (Intel P4 / Pentium D) and the PE2400, PE 2600, PE2800 servers (Intel
> Xeon). The design is completely different. The air is sucked in from the
> front of the case, straight over the CPU and out of the back - how cool
> is that? Pretty cool, and there's hardly any noise either.
>
> --
> Gerry_uk
My Gigabyte Aurora pulls air in from front bottom via 120mm fan and then
expels it from the back via two 120mm fans at middle and top of chassis.
Now, if I position the Zalman 9500 so that its fan intake side is parallel
to the front of the case(facing it), then the CPU cooler should actually
help facilitate the cooling air flow as the external air is pulled in from
front bottom, passed through the CPU cooler fan/fins and proceeds out the
back. No whirling flow patterns, just a nice line through the case and over
the motherboard. Only problem: My OCZ PS has a fan underneath its case
pointing downward at the mobo with another out the back. Hopefully, this
downward fan actually sucks air up through the PS box and out the back. If
so, it will probably add even more to the air evac. If not, then there's a
flow conflict. We'll see when I get it all hooked up. But there is no other
fan blowing air down from above and I've never seen any ATX case that
deliberately does this either. Only from PSUs that have bottom fans. My old
Supermicro full tower does the exact same thing. Cool air from front bottom
to exhaust fans back top. This isn't new thermal management, they've been
doing this for awhile. Even side air duct cases have been out for awhile.
On Sat, 23 Sep 2006 23:06:52 +0100, Gerry_uk
<gerry666uk@yahoo.com> wrote:
>Hi,
>
>As I understand it, most ATX style PC setups have a fan above the CPU
>that blows air down onto the CPU to keep it cool, and the hot air
>bounces around inside the PC case until it can find an exit (if it's lucky).
No, a properly set up case has a bottom front intake and a
center and top rear exhaust. Heated air exhausted out of
the heatsink is moving towards the exhaust fans at all
times. A small percentage of it will get recirculated back
though the heatsink, BUT, attempts to change this will
typically reduce overall airflow, so it can have a
diminishing return (or even be worse) trying to minimize
recirculation.
>
>As I see it, there are two problems with this,
>
>a) unless you have a vent in the side of the PC case, the air being
>taken in by the CPU cooler will not be cool, because it's air from
>inside the PC case?
You do not want a vent in the side unless the entire system
is set up to still maintain reasonable airflow considering
the effect of that side vent.
Remember one very important factor in proper system setup:
Each part is supposed to have adequate heat removal method,
including sufficient 'sink. The focus is never to try to
get CPU the most air, nor most cool air. Incoming air does
as described above, comes on the bottom front and travels
towards the top rear. It is supposed to remove the heat
from the HDDs, southbridge or single-chip on motherboard,
flow by the video card, and anything else in this lower/mid
region. If you try to change this flow by drawing in air
near the CPU, you will necessarily reduce cooling of the
other parts unless other addt'l accomdations are made to
cool them.
The CPU has a huge heatsink on it, these other parts do not
(even video card, is not usually "huge" in comparison). The
other parts depend on the passive airflow while the CPU has
a fan.
>
>b) the hot air from the bottom of the heat sink ends up warming up the
>Motherboard?
It doesn't matter because:
1) The air is not extremely hot, parts that don't produce
much heat can stand to be a little warmer than they would
have been had there been no CPU heat.
2) The few parts that are warmer than this heated air, will
be cooled by it still.
>
>I was looking at the Dell CPU coolers of the GX280, GX620 workstaions
>(Intel P4 / Pentium D) and the PE2400, PE 2600, PE2800 servers (Intel
>Xeon). The design is completely different.
No, the design is exactly the same, except they do without
the CPU sink fan by putting a duct on the rear.
It can be quieter, or it can be same noise level as a
well-designed system. The reason for this is that the rear
fan has to spin faster because of the snorkel, and because
you wouldn't be comparing apples:apples if only considering
systems that don't use RPM-reduced throttling of the fans as
the Dell systems typically do.
The reality is that Dell saves $1 or 2 by eliminating one
fan, but if a system is not budget constrained (or profit
maximized, however you want to look at it), the alternative
system can run cooler than Dell's can, because the rear fan
can more more air without the duct, and a heatsink with a
fan on it can have that fan running at low enough RPM that
it is not descriminable over the noise of the rear fan (what
little there is).
In the end, there is one simple truth: You have a case that
has parts producing X amount of heat. The heat buildup of
the parts inside depends on the total airflow rate in and
out of the system. When Dell uses the snorkel on the rear
fan, it has a lower airflow:noise ratio and thus, for the
given level of noise the lower airflow does not get the heat
out as fast, the chassis internal temp average is higher.
In some systems, spot-measurements of a given component will
be cooler in the Dell system. In others, warmer in the
Dell. On average, the Dell will be warmer overall, so if
you are concerned about CPU heat as it appeared when
starting your post, the most significant factor may be
whether the heatsink quality is better than Dell's or not.
It is a large market with many different 'sinks, some are
better, others are worse.
>The air is sucked in from the
>front of the case, straight over the CPU and out of the back - how cool
>is that? Pretty cool, and there's hardly any noise either.
Cool? That's how many OEM systems have been set up for
years. If you want you can build your own like this, all
you need is to fabricate your own rear exhaust snorkel and a
suitable heatsink designed for passive cooling (typically
tall wider spaced tines instead of shorter, denser spaced
fins).
>the dell solution is the BX rather than the ATX cooling
>
On today's new systems, yes, but we have no idea which the
OP is looking at to make the observation... Dell has been
doing similar to what was described for years, as have other
OEMs.
"Gerry_uk" <gerry666uk@yahoo.com> wrote in message
news:1159049196.61449.0@demeter.uk.clara.net...
> Hi,
>
> As I understand it, most ATX style PC setups have a fan above the
> CPU that blows air down onto the CPU to keep it cool, and the hot
> air bounces around inside the PC case until it can find an exit (if
> it's lucky).
>
> As I see it, there are two problems with this,
>
> a) unless you have a vent in the side of the PC case, the air being
> taken in by the CPU cooler will not be cool, because it's air from
> inside the PC case?
>
> b) the hot air from the bottom of the heat sink ends up warming up
> the Motherboard?
>
> I was looking at the Dell CPU coolers of the GX280, GX620
> workstaions (Intel P4 / Pentium D) and the PE2400, PE 2600, PE2800
> servers (Intel Xeon). The design is completely different. The air is
> sucked in from the front of the case, straight over the CPU and out
> of the back - how cool is that? Pretty cool, and there's hardly any
> noise either.
You could cut a hole in the side panel and put a shroud around the CPU
fan so fresh cooler air gets sucked in and immediately used to cool
the CPU rather than on relying on air that has entered a foot or more
away and been pre-warmed by hard drives, memory sticks, Northbridge
chip, or whatever is between the front case grill and the CPU.
"Vanguard" <vanguard.news@yahooNIX.com> wrote in message
news:ef4l9v$vaf$1@emma.aioe.org...
> "Gerry_uk" <gerry666uk@yahoo.com> wrote in message
> news:1159049196.61449.0@demeter.uk.clara.net...
> > Hi,
> >
> > As I understand it, most ATX style PC setups have a fan above the
> > CPU that blows air down onto the CPU to keep it cool, and the hot
> > air bounces around inside the PC case until it can find an exit (if
> > it's lucky).
> >
> > As I see it, there are two problems with this,
> >
> > a) unless you have a vent in the side of the PC case, the air being
> > taken in by the CPU cooler will not be cool, because it's air from
> > inside the PC case?
> >
> > b) the hot air from the bottom of the heat sink ends up warming up
> > the Motherboard?
> >
> > I was looking at the Dell CPU coolers of the GX280, GX620
> > workstaions (Intel P4 / Pentium D) and the PE2400, PE 2600, PE2800
> > servers (Intel Xeon). The design is completely different. The air is
> > sucked in from the front of the case, straight over the CPU and out
> > of the back - how cool is that? Pretty cool, and there's hardly any
> > noise either.
>
>
> You could cut a hole in the side panel and put a shroud around the CPU
> fan so fresh cooler air gets sucked in and immediately used to cool
> the CPU rather than on relying on air that has entered a foot or more
> away and been pre-warmed by hard drives, memory sticks, Northbridge
> chip, or whatever is between the front case grill and the CPU.
>
I was under the impression that you just want the hot air drawn off the
components. I'm not so sure I'd want cool air pumped over my CPU. What
happens when a cold front hits a warm front? I'm not suggesting it would
rain inside my case, but wouldn't condensation come into play? My box will
be in an AC environment and sometimes that cool air is actually cold. Now
maybe the hot components stay hot enough to evaporate that, but just to make
sure, I'll throw a couple of silicon packs in the bottom of my case. Think
that'll help? : )
"Ron Krebs" <rkrebs11@verizon.net> wrote in
news:GglRg.1011$fl2.452@trnddc02:
> I was under the impression that you just want the hot air drawn off
> the components. I'm not so sure I'd want cool air pumped over my CPU.
> What happens when a cold front hits a warm front? I'm not suggesting
> it would rain inside my case, but wouldn't condensation come into
> play? My box will be in an AC environment and sometimes that cool air
> is actually cold. Now maybe the hot components stay hot enough to
> evaporate that, but just to make sure, I'll throw a couple of silicon
> packs in the bottom of my case. Think that'll help? : )
When the cool air hits the warm stuff inside the case it will get warmer
and the relative humidity of that air will drop. If you had cold stuff in
the case and you were pumping warm outside air onto it then you might have
a condensation problem, as can occur with some extreme phase-change type
coolers.
"Mitch Crane" <a-one@a-two.a-three> wrote in message
news:Xns9848BA19AA2aoneatwoathree@216.196.97.140.. .
> "Ron Krebs" <rkrebs11@verizon.net> wrote in
> news:GglRg.1011$fl2.452@trnddc02:
>
>> I was under the impression that you just want the hot air drawn off
>> the components. I'm not so sure I'd want cool air pumped over my
>> CPU.
>> What happens when a cold front hits a warm front? I'm not
>> suggesting
>> it would rain inside my case, but wouldn't condensation come into
>> play? My box will be in an AC environment and sometimes that cool
>> air
>> is actually cold. Now maybe the hot components stay hot enough to
>> evaporate that, but just to make sure, I'll throw a couple of
>> silicon
>> packs in the bottom of my case. Think that'll help? : )
>
> When the cool air hits the warm stuff inside the case it will get
> warmer
> and the relative humidity of that air will drop. If you had cold
> stuff in
> the case and you were pumping warm outside air onto it then you
> might have
> a condensation problem, as can occur with some extreme phase-change
> type
> coolers.
Guess Ron forgot that the air is *dryer* in winter when the air is
colder hence the higher sales of humidifiers in winter. Silicon packs
are useless when air is moving. They are used in sealed containers to
remove what moisture is there and would be *trapped* there.
"Vanguard" <vanguard.news@yahooNIX.com> wrote in message
news:ef6c4h$plj$1@emma.aioe.org...
> "Mitch Crane" <a-one@a-two.a-three> wrote in message
> news:Xns9848BA19AA2aoneatwoathree@216.196.97.140.. .
> > "Ron Krebs" <rkrebs11@verizon.net> wrote in
> > news:GglRg.1011$fl2.452@trnddc02:
> >
> >> I was under the impression that you just want the hot air drawn off
> >> the components. I'm not so sure I'd want cool air pumped over my
> >> CPU.
> >> What happens when a cold front hits a warm front? I'm not
> >> suggesting
> >> it would rain inside my case, but wouldn't condensation come into
> >> play? My box will be in an AC environment and sometimes that cool
> >> air
> >> is actually cold. Now maybe the hot components stay hot enough to
> >> evaporate that, but just to make sure, I'll throw a couple of
> >> silicon
> >> packs in the bottom of my case. Think that'll help? : )
> >
> > When the cool air hits the warm stuff inside the case it will get
> > warmer
> > and the relative humidity of that air will drop. If you had cold
> > stuff in
> > the case and you were pumping warm outside air onto it then you
> > might have
> > a condensation problem, as can occur with some extreme phase-change
> > type
> > coolers.
>
>
> Guess Ron forgot that the air is *dryer* in winter when the air is
> colder hence the higher sales of humidifiers in winter. Silicon packs
> are useless when air is moving. They are used in sealed containers to
> remove what moisture is there and would be *trapped* there.
>
I sure did. Problem is, I don't run my box outside in cold, dry winter air.
Nope, it's in an AC environment where they run plenty of humidifiers. And
I'm disappointed my attempt at humor with the silicon packs was taken
literally. I guess I'll have to make a bigger smiley next time. Cheers,
"Ron Krebs" <rkrebs11@verizon.net> wrote in message
news:prARg.1486$KK.159@trnddc08...
>
> "Vanguard" <vanguard.news@yahooNIX.com> wrote in message
> news:ef6c4h$plj$1@emma.aioe.org...
>> "Mitch Crane" <a-one@a-two.a-three> wrote in message
>> news:Xns9848BA19AA2aoneatwoathree@216.196.97.140.. .
>> > "Ron Krebs" <rkrebs11@verizon.net> wrote in
>> > news:GglRg.1011$fl2.452@trnddc02:
>> >
>> >> I was under the impression that you just want the hot air drawn
>> >> off
>> >> the components. I'm not so sure I'd want cool air pumped over
>> >> my
>> >> CPU.
>> >> What happens when a cold front hits a warm front? I'm not
>> >> suggesting
>> >> it would rain inside my case, but wouldn't condensation come
>> >> into
>> >> play? My box will be in an AC environment and sometimes that
>> >> cool
>> >> air
>> >> is actually cold. Now maybe the hot components stay hot enough
>> >> to
>> >> evaporate that, but just to make sure, I'll throw a couple of
>> >> silicon
>> >> packs in the bottom of my case. Think that'll help? : )
>> >
>> > When the cool air hits the warm stuff inside the case it will get
>> > warmer
>> > and the relative humidity of that air will drop. If you had cold
>> > stuff in
>> > the case and you were pumping warm outside air onto it then you
>> > might have
>> > a condensation problem, as can occur with some extreme
>> > phase-change
>> > type
>> > coolers.
>>
>>
>> Guess Ron forgot that the air is *dryer* in winter when the air is
>> colder hence the higher sales of humidifiers in winter. Silicon
>> packs
>> are useless when air is moving. They are used in sealed containers
>> to
>> remove what moisture is there and would be *trapped* there.
>>
>
> I sure did. Problem is, I don't run my box outside in cold, dry
> winter air.
> Nope, it's in an AC environment where they run plenty of
> humidifiers.
If it is cooler inside your PC's box than outside, why are you pumping
warm air into it to cause condensation problem?
>On Mon, 25 Sep 2006 06:54:20 -0500, "Vanguard"
><vanguard.news@yahooNIX.com> wrote:
>
>>>
>
>The point is to continually "change the air" inside your case to keep
>your components cooler. Whether you have air blowing in (and the air
>inside air is forced out) or you have fans blowing out (and outside
>air is drawn in) really makes no difference. I have fans blowing in
>near the bottom and the fan near the top, including the power supply,
>blowing out.
>
>I saw a case mod where the guy had a duct from his AC going directly
>into his case and it still wasn't raing or iceing up in there.
The problem is not pumping cold air into a warm case, it
would be pumping warm air into a cold case.
| I saw a case mod where the guy had a duct from his AC going directly
| into his case and it still wasn't raing or iceing up in there.
An AC vent directs cold air toward the front on my computer case where there are
two fans drawing air in. When the AC is on, CPU and mobo temps sometimes report
at less than room temp, especially soon after I turn the system on. Yet, I
never have condensation problems.
Larc
§§§ - Change planet to earth to reply by email - §§§
On Sat, 23 Sep 2006 23:06:52 +0100, Gerry_uk <gerry666uk@yahoo.com>
wrote:
>Hi,
>
>As I understand it, most ATX style PC setups have a fan above the CPU
>that blows air down onto the CPU to keep it cool, and the hot air
>bounces around inside the PC case until it can find an exit (if it's lucky).
>
>As I see it, there are two problems with this,
>
>a) unless you have a vent in the side of the PC case, the air being
>taken in by the CPU cooler will not be cool, because it's air from
>inside the PC case?
>
>b) the hot air from the bottom of the heat sink ends up warming up the
>Motherboard?
>
>I was looking at the Dell CPU coolers of the GX280, GX620 workstaions
>(Intel P4 / Pentium D) and the PE2400, PE 2600, PE2800 servers (Intel
>Xeon). The design is completely different. The air is sucked in from the
>front of the case, straight over the CPU and out of the back - how cool
>is that? Pretty cool, and there's hardly any noise either.
>
So what ??
That's exactly the way it is in conjunction with my rear case fan and
vented front-panel with my Zalman9500 @ 1600RPM on my X2 4400+
( o/c'd to 2.6GHz, absolute max. case temp 48 degrees C). Cools the
memory very effectively as well. The Zalman design is quite brilliant
for its efficiency and smart airflow pattern while still only slightly
over the CPU manufacturer's max. recommended heatsink weight. Which
is no worry on my A8N32-SLI with the provided board-stiffener
in the CPU area.
I am not familiar with the Dell hardware you describe ? BTX-style by
any chance ? In which case a high-performance video card will nicely
bake in the exhaust air from the CPU and memory area. Not surprising
in a totally CPU-centric motherboard design from the same wizards that
brought you the hand and foot-warmer called the P4-Prescott.
<techdude@msft.com> wrote in message
news:q1ofh2lr3dk23896253i6ja6d8v4g2v5pp@4ax.com...
> On Mon, 25 Sep 2006 06:54:20 -0500, "Vanguard"
> <vanguard.news@yahooNIX.com> wrote:
>
>>>
>
> The point is to continually "change the air" inside your case to
> keep
> your components cooler. Whether you have air blowing in (and the air
> inside air is forced out) or you have fans blowing out (and outside
> air is drawn in) really makes no difference. I have fans blowing in
> near the bottom and the fan near the top, including the power
> supply,
> blowing out.
>
> I saw a case mod where the guy had a duct from his AC going directly
> into his case and it still wasn't raing or iceing up in there.
Because your friend had the smarts to blow *colder* air into the case
so there would be no condensation when it hit the warmer parts.
Blowing air out the side panel means you are sucking in pre-warmed air
over the CPU before exhausting it. Blowing air into the case directly
at the CPU means you get the greatest temperature differential. Since
the PSU is nearby, the air warmed by the CPU gets drawn out and
exhausted through the PSU rather than over the memory sticks or
chipset. Either just use a hole and shroud with the existing CPU fan
or use a case fan with shroud in place of the CPU fan. Do no have a
case fan next to the CPU fan (but if you feel the need then make damn
sure they blow in the SAME direction and not at or away from each
other). One of the fans will end up restricting the other regarding
maximum airflow. If one blows more CFM than the other then the lesser
CFM fan acts as resistance to the higher CFM fan. This is the same
reason why you need to make sure your case's air intake matches or
exceeds your case's exhaust rate since you can't push out more than
you can suck in (although some have said a slight positive air
pressure inside the case reduces dust accumulation, but I've never
measure the amount of dust collected in my case and simply realize
that I need to blow it out twice a year).
Remember that while a greater temperature differential, using
water-cooled systems, peltier setups, or whatever that you are simply
increasing the possibility of cooling your components as much as
possible. You can't cool them faster than the thermal interface
allows; i.e., you could easily use excessive cooling beyond which the
heat cannot transfer across a metal plate any faster, so the extra
cooling is wasted. Similarly, for air cooling, buying a CPU fan that
is rated 50 CFM won't push that amount of air through the restrictive
air space between the heatsink fins (the fins cause turbulence and the
airflow has to take a 90-degree turn both of which equate to
resistance). You might find a 25 CFM fans cools just as well as a
much noisier 50 CFM fan. In fact, I've seen CPU and case temperatures
drop in some cases by reversing the backpanel fan so it is an intake
fan rather than an exhaust fan (its normal position) but you need to
test in your own case.
On Mon, 25 Sep 2006 22:38:03 -0500, "Vanguard"
<vanguard.news@yahooNIX.com> wrote:
>Blowing air out the side panel means you are sucking in pre-warmed air
>over the CPU before exhausting it. Blowing air into the case directly
>at the CPU means you get the greatest temperature differential. Since
>the PSU is nearby, the air warmed by the CPU gets drawn out and
>exhausted through the PSU rather than over the memory sticks or
>chipset.
Blowing air in (or having no side fan at all) results in the
most pre-heated air flowing over the memory or chipset.
Granted, the air might be slightly cooler.
The key to reducing warm air flowing in circular or
counterproductive directions is to not interfer with the
time-tested and proven chassis airflow pattern from bottom
front to mid-top rear.
By reducing the bottom front intake rate, by use of a side
intake if not another method, there are lower velocity flow
everywhere except into the 'sink. The exhaust fans will
exhaust at same rate (providing front intake was sufficient)
but a short-loop is created, any air not exhausted into the
air most immedate to the exhaust fan will take a longer path
till exhausted, and slower.
Side intake is mostly Intel's attempt to ship cheaper
heatsinks with P4, particularly Prescott CPUs. A properly
set up system has no need for the side intake and is usually
as well off having it blocked completely. The CPU is not
the only part that needs cooled and the heatsink selected
for it should be selected so as to do the job acceptibly
without other parts running warmer as a result.
>Remember that while a greater temperature differential, using
>water-cooled systems, peltier setups, or whatever that you are simply
>increasing the possibility of cooling your components as much as
>possible. You can't cool them faster than the thermal interface
>allows;
Untrue/non-applicable. The thermal interface doesn't allow
or disallow, it is only a decrease in efficiency of transfer
from the warmer to the cooler part. This warm vs cool is
the key element as mentioned below.
>i.e., you could easily use excessive cooling beyond which the
>heat cannot transfer across a metal plate any faster, ...
False. If the cooling isn't much better, the difference may
not be significant change in temp (only a little), and the
CPU may not have needed to run cooler at all, BUT it will
run cooler with a better cooling system and exact same
thermal interface, because the better cooling results in the
cooler of the two parts (warm vs cool), being cooler than it
would have been. Thus, the thermal compound with the same
thermal transfer efficiency, is seeing a higher temp
differential between the two parts which must necessarily
result in a cooler CPU (all else being equal, same thickness
of thermal grease, flatness of mating parts, contact area to
top of CPU, etc).
> ... so the extra
>cooling is wasted.
It might easily be wasted money, time, even materials to
throw away the stock sink (and years(?) later this 2nd sink)
if there wasn't a specific *need* to get the CPU any cooler
(like in an extremely hot environment or high overclocking),
if it ran cool enough to be stable and have acceptible
lifespan, OR if the improvement in the cooling was minimal,
such a slight drop in temp that it varies more by ambient
room temp than anything else.
>Similarly, for air cooling, buying a CPU fan that
>is rated 50 CFM won't push that amount of air through the restrictive
>air space between the heatsink fins (the fins cause turbulence and the
>airflow has to take a 90-degree turn both of which equate to
>resistance).
A higher free-air rated fan will not push the free-air
volume through a heatsink, that much is true. On the other
hand, given a similar fan (dimensionally matching the other
fan and heatsink and at least as thick) that has the higher
CFM from higher RPM, that will result in more airflow
through the 'sink. Perhaps not a lot more- these fans have
relatively low static pressure potential, but even a little
more, will directly correspond to a reduction in heatsink
temp, which as mentioned above, will ultimately cool the CPU
more.
Increasing airflow has a quickly diminishing return though,
Seldom is it worthwhile to have a fan faster than around
3000 RPM unless a special circumstance or very poor fan
(typically undersized or at least too thin for the
application). Often it is desirable to have even lower RPM,
it can be acceptible to have CPU slightly hotter to
significantly decrease noise if the margin allows for it.
>You might find a 25 CFM fans cools just as well as a
>much noisier 50 CFM fan.
If all else were equal, no, it is impossible. If the
diameter of fan or thickness, or even an entirely odd
proprietary fan design were used on same heatsink, then
these other factors would have to be considered as well, but
taking same exact fan one can vary the voltage to produce
different RPM -> airflow (airflow will increase so long as
the fan isn't terribly undersized and already at it's
practical maximum flow rate into the pressurized area in the
'sink) and see the temp change. It may not change a lot
but it is an inescapable scientific truth that to whatever
extent this air (which is cooler than the 'sink) flow is
increased, there will be a corresponding decrease in 'sink
fin temp, conduction away from the base of the 'sink to this
lower temp region of the fins, and through the thermal
compound to the CPU. The conduction efficiency does not
change with the fixed variables (grease, heatsink metal) but
across mediums (CPU to 'sink or 'sink to air) the higher
temp differential does always result in lower temp.
Naturally if the temp difference is minor, especially if
being reported by a motherboard-mounted sensor, it may be so
slight a change as to be indiscriminable. I am not
suggested anyone improve their cooling at all, unless it is
overheating.
>In fact, I've seen CPU and case temperatures
>drop in some cases by reversing the backpanel fan so it is an intake
>fan rather than an exhaust fan (its normal position) but you need to
>test in your own case.
This should never be done, it necessarily increases temps of
other parts (unless the case was otherwise unusual in it's
airflow before this fan was flipped over). Cooling a CPU is
not a game where lowest number wins. Anyone who has a
stable system and CPU that doesn't die prematurely, "wins",
so long as they deem the noise level acceptible. However,
while keeping the CPU cool enough, focus is then shifted to
the rest of the system - a CPU is more heat tolerant than
many parts.
> A properly
> set up system has no need for the side intake and is usually
> as well off having it blocked completely.
Perhaps, but here's something to try.
Run your ordinary ATX fan cooled PC for two hours in the summer
including some time under load. Measure the CPU and MB temps, then
remove the side panel near the CPU, watch the temps FALL like a brick!
> Blowing air in (or having no side fan at all) results in the
> most pre-heated air flowing over the memory or chipset.
> Granted, the air might be slightly cooler.
Ah, who needs fans? For peace and quiet you want one of these:
"kony" <spam@spam.com> wrote in message
news:ogcih2l0umjm35h7rokab691gt1egn3rtf@4ax.com...
> On Mon, 25 Sep 2006 22:38:03 -0500, "Vanguard"
> <vanguard.news@yahooNIX.com> wrote:
>
>
>>Blowing air out the side panel means you are sucking in pre-warmed
>>air
>>over the CPU before exhausting it. Blowing air into the case
>>directly
>>at the CPU means you get the greatest temperature differential.
>>Since
>>the PSU is nearby, the air warmed by the CPU gets drawn out and
>>exhausted through the PSU rather than over the memory sticks or
>>chipset.
>
> Blowing air in (or having no side fan at all) results in the
> most pre-heated air flowing over the memory or chipset.
> Granted, the air might be slightly cooler.
Slightly cooler? Try 15 C cooler. While my room temperature is 20 C,
the inside temperature is 35 C (no, I haven't gotten to modding my
home PC's case yet). Actually I prefer a quiet PC so I let Speedfan
slow down the fans which lets the inside get hotter unless
temperatures exceed the configured thresholds whereupon the fans speed
up and are more noisy. Cooler internal temperatures would mean cooler
air over the CPU (and GPU). Having to push warmer air over the CPU
means less efficient cooling. If I can get MORE cooler outside air
inside the case then there would be fewer times when Speedfan would
have to speed up the fans.
> The key to reducing warm air flowing in circular or
> counterproductive directions is to not interfer with the
> time-tested and proven chassis airflow pattern from bottom
> front to mid-top rear.
Time-tested? Time has shown that the ATX case was NOT designed for
best cooling. It provides absolutely no zoning of airflow. In fact,
it stupidly enforces turbulence because of the twisting required for
the airflow, and turbulence is resistance to airflow. Do you see any
ATX-style cases that have channels built in to keep flat cables out of
the way so they don't block the airflow? Why did they design it so
hard drives could be shoved against each other (so there is no airflow
between them)? Low front intake is okay for drives in the lower cage
but not in the upper drive cage. ATX (without modification) is a poor
design for cooling.
> By reducing the bottom front intake rate, by use of a side
> intake if not another method, there are lower velocity flow
> everywhere except into the 'sink. The exhaust fans will
> exhaust at same rate (providing front intake was sufficient)
> but a short-loop is created, any air not exhausted into the
> air most immedate to the exhaust fan will take a longer path
> till exhausted, and slower.
Short loops are exactly what are needed for zoning the airflows to
minimize them from intermingling with each other. Cool the hot stuff
first with direct outside air and expel it immediately.
> Side intake is mostly Intel's attempt to ship cheaper
> heatsinks with P4, particularly Prescott CPUs.
Wrong. Side intake was to circumvent the ATX spec's poor airflow
design.
> The CPU is not the only part that needs cooled
Exactly, so why use the same airflow to cool EVERYTHING? ATX is a
poor design for cooling. Modders knew that for a long time before
case makers starting adding the extra intake/exhaust ports.
>>In fact, I've seen CPU and case temperatures
>>drop in some cases by reversing the backpanel fan so it is an intake
>>fan rather than an exhaust fan (its normal position) but you need to
>>test in your own case.
>
> This should never be done, it necessarily increases temps of
> other parts (unless the case was otherwise unusual in it's
> airflow before this fan was flipped over).
Not if you add MORE venting, like adding a top grill and a bottom fan
that pushes air up past the rear of the drive cages and over the
memory sticks. Top venting may simply be using a PSU that has a
grilled front face instead of just a few slits. I get much better
cooling for *everything* by zoning the airflow inside the case. The
CPU gets cool air from the side panel and its heated air passes out
through the backpanel grill (using shrouds). The daughtercards (i.e.,
video) get their own shroud to pull in air from the side panel intake
and out through a rear grill over the cards (get a fat case to add the
grill or buy one with it already there). Add a grill to the bottom
with a fan to blow up and past the backside of the drive cages and
over the memory sticks (add a top grill if you feel the PSU's fan
isn't adequate or it doesn't have a grilled front face). Keep airflow
as linear as possible and minimize turbulence (which includes changes
in direction).
Many cases don't have fans at the front (unless YOU add them) but
instead just passively suck in the air based on the effective rate of
the exhaust fans. If you now add an intake port midstream in the
case, as in the case of a side panel intake fan, the exhaust fans will
be expelling a portion of that air and drawing less in from the front.
You might end up having to add a fan at the front or around the hard
drives to make sure they get sufficiently cooled, too. If the exhaust
fans were expelling 30 CFM (as their maximum) but a new hole is added
at the side that inputs 10 CFM, the exhaust fans are still only going
to expel 30 CFM so 10 CFM less is coming in from the front to cool the
other parts. So, yeah, I see your point but my point is that the ATX
design sucks for cooling. Better cooling was NOT why the ATX spec was
developed.
Almost everyone has seen that taking off the side panel and simply
pointing a table fan into the case lowers temperatures significantly,
so regardless of the ancient ATX case design, you could use side panel
intake fans to better cool your system provided there was an
equivalent rate of exhaust and you don't mind the noise of the extra
fans.
The ATX design doesn't cool that well so sometimes we have to mod the
case to cool *better*. The old ATX design tried to use one major
airflow pattern to cool off everything. Remember that the first ATX
spec had the PSU blowing air into the case and they later decided it
was better to have the PSU fan suck it out. If you read the ATX 2.1
spec (http://www.formfactors.org/developer/specs/atx2_1.pdf), all it
says about airflow is "Chassis venting should be placed strategically
to allow for
proper cooling of other components such as peripherals and add-in
cards." Oooh, wow, what a scientific airflow design ... not! ATX was
designed for *cheap* integration, not for best cooling. The only part
of the spec that addresses specific airflow is in the placement of the
PSU and its fan in close proximity to the CPU to quickly expel the
heat generated by the CPU so doesn't travel to warm up other
components.
Don't get too hung up on claiming the ATX case was designed for a
particular airflow pattern for best cooling. Its spec was NOT
designed for best cooling and its up to you to mod the case (or get
one) based on YOUR cooling needs and component placement. Obviously
you could mod it wrong but it's pretty easy to mod it right and get
far better results than what the ATX spec was designed for which
itself tells you to mod according to your needs. Designers came up
with BETTER cooling designs while sticking within the ATX footprint,
that's why there are cases with extra intake/exhaust ports (but not
all have them strategically placed). If the ATX design really had
considered cooling, it would've zoned the areas to be cooled where,
for the hottest components, outside air is drawn immediately to a hot
component and expelled immediately without it mingling with any other
airflows. If you're hot and sweaty, do you turn on the fan and stand
on the other side of the room? Do you stand behind some other hot and
sweaty person or go get your own fan? Cooling can be VASTLY improved
over the ancient and inadequate ATX-style case. If you can cut
plexiglass (and heat to bend it, if needed) and glue it together to
make your own shrouds (or find a kit that works for you), along with
nibbling to add fans and intake/exhaust grills, you can zone your own
case and get it running almost as cool (for EVERYTHING) as you could
by simply removing the side panel and pointing a table fan at the
innards.
On Tue, 26 Sep 2006 20:55:53 +0100, Gerry_uk
<gerry666uk@yahoo.com> wrote:
>Hi kony,
>
>> A properly
>> set up system has no need for the side intake and is usually
>> as well off having it blocked completely.
>
>Perhaps, but here's something to try.
>
>Run your ordinary ATX fan cooled PC for two hours in the summer
>including some time under load. Measure the CPU and MB temps, then
>remove the side panel near the CPU, watch the temps FALL like a brick!
If your ambient (room) temp is much higher in summer, it
might be better to make the room hospitible to the user, and
have the system benefit as a side-effect.
If the system is intended to be used in hot environment,
this should be taken into account when designing or
modifying the system cooling.
If you take the side panel off and get lower temp, the real
question is whether the temp was too high before you took it
off. The secondary issue (still quite important) is whether
the OTHER parts are as cool. In general, taking the side
panel off will tend to make the HDDs and other lower-front
quadrant parts run hotter than with it on. Never forget
that the CPU is not the only part that needs to run cool
enough, it is merely the one most people are overly fixated
on- and yet it has a large heatsink.
A balanced system, properly set up, will have a CPU heatsink
of acceptible size. It should never be necessary to remove
the side panel and enough airflow to keep the other
components cool enough, is likewise enough airflow to keep
CPU cool enough. If it is not cool enough and the other
components are, the solution is a heatsink upgrade or to
increase chassis airflow (but the latter increases noise
more than the former, assuming "heatsink upgrade" doesn't
mean merely choosing one with a higher RPM fan on it).
On Tue, 26 Sep 2006 22:19:22 -0500, "Vanguard"
<vanguard.news@yahooNIX.com> wrote:
>"kony" <spam@spam.com> wrote in message
>news:ogcih2l0umjm35h7rokab691gt1egn3rtf@4ax.com.. .
>> On Mon, 25 Sep 2006 22:38:03 -0500, "Vanguard"
>> <vanguard.news@yahooNIX.com> wrote:
>>
>>
>>>Blowing air out the side panel means you are sucking in pre-warmed
>>>air
>>>over the CPU before exhausting it. Blowing air into the case
>>>directly
>>>at the CPU means you get the greatest temperature differential.
>>>Since
>>>the PSU is nearby, the air warmed by the CPU gets drawn out and
>>>exhausted through the PSU rather than over the memory sticks or
>>>chipset.
>>
>> Blowing air in (or having no side fan at all) results in the
>> most pre-heated air flowing over the memory or chipset.
>> Granted, the air might be slightly cooler.
>
>Slightly cooler? Try 15 C cooler.
Only if the case wasn't designed properly. CPU temp rise is
in direct correlation to chassis ambient temp and the
chassis should not be 15C hotter. If the chassis is that
hot, the other parts were suffering too and putting in the
side duct may make them even hotter.
Remember the system is not only comprised of a CPU, if the
CPU as hot, so are other parts that you may not be
monitoring actively- and if you aren't monitoring them
actively, it can be even more important to have a larger
thermal margin.
>While my room temperature is 20 C,
>the inside temperature is 35 C (no, I haven't gotten to modding my
>home PC's case yet).
What are you using to determine the case temp? If you rely
on the "system" or "case" temp resport via software, I
presume you realize that is often not the actual chassis air
temp but rather, of a different chip that produces it's own
heat.
>Actually I prefer a quiet PC so I let Speedfan
>slow down the fans which lets the inside get hotter unless
>temperatures exceed the configured thresholds whereupon the fans speed
>up and are more noisy. Cooler internal temperatures would mean cooler
>air over the CPU (and GPU). Having to push warmer air over the CPU
>means less efficient cooling. If I can get MORE cooler outside air
>inside the case then there would be fewer times when Speedfan would
>have to speed up the fans.
There is no need to speed up the fans at 35C, so there is
either more significant information lacking in your
description, or another issue (which is likely chassis
airflow, if the actual chassis air temp is 15C above room
ambient). Even if the latter is true, we can ignore the CPU
temp and not throttle up fans, rather focusing on the other
parts. Remember that the CPU is more heat resistant than
many of them, and has a longer expected lifespan too.
>
>> The key to reducing warm air flowing in circular or
>> counterproductive directions is to not interfer with the
>> time-tested and proven chassis airflow pattern from bottom
>> front to mid-top rear.
>
>Time-tested?
Yes
>Time has shown that the ATX case was NOT designed for
>best cooling.
"Best" is arbitrary if you only focus on CPU temp,
particularly when you describe above a CPU that is not even
remotely close to overheating!
>It provides absolutely no zoning of airflow.
Wrong, it does far better than having a side duct. WIthout
the side duct there is a clear airflow path from bottom
front to mid-top rear. Add the side duct and the bottom
front will necessarily have lower airflow rate.
>In fact,
>it stupidly enforces turbulence because of the twisting required for
>the airflow,
Turbulence ON the parts being cooled is exactly what you
want. Turbulence in the rest of the case is minimal, it is
proven so and WAS TESTED when ATX was spec'd. They didn't
ignore cooling of everything but the CPU though, which seems
to be what you are doing even when CPU is far cooler than it
needs be.
>and turbulence is resistance to airflow.
Inside a chassis that is much larger than the intake or
exhaust areas, the effect of turbulence is minimal, beyond
consideration.
>Do you see any
>ATX-style cases that have channels built in to keep flat cables out of
>the way so they don't block the airflow?
It is a marketing feature unless the system integrator has
no idea how to route cables properly. Plenty of system
builders have demonstrated, millions of times, that a case
with ribbon cables and no channels built in will run fine IF
the primary considerations are considered- and they don't
require a side duct, rather as mentioned previously, the
side duct interferes with airflow around cables by reducing
the amount of airflow in this region. IF your side-duct
was blowing out of the case instead of in, it would increase
the airflow around drives, cables, but this then decreases
airflow around (many if not all) CPU VRM circuits, and out
the PSU, and possibly through the CPU heatsink too.
>Why did they design it so
>hard drives could be shoved against each other (so there is no airflow
>between them)?
Your proposition of the side duct does not change this, only
further reducing airflow there.
Further, you only assume they designed to have drives
"shoved up", when in actuality it was case manufacturers
that only tried to put the most drives in the least space
possible that resulted in the "shoved" scenario.
>Low front intake is okay for drives in the lower cage
>but not in the upper drive cage. ATX (without modification) is a poor
>design for cooling.
Drives in the upper cage are also cooled worse if you
introduce a side duct, unless you had the duct opposite the
rack (which is almost never done, it's far lower).
A better question is why you feel they are not cooled well?
Optical drives do not need a lot of airflow, those that are
particularly hot running tend to have a fan in their casing
but once designs that weren't so hot were produced, the fans
were eliminated. If you have a hard drive up there, you are
choosing to not adhere to the normal component placement and
as such, are taking it upon your self to provide a front
intake (perforated if not actively fan cooled) front
faceplate to accomodate this change in drive location.
ATX does accomodate drives fine, if you don't assume some
poorly made case defines what ATX is, rather than the truth-
that ATX is the definition and the poorly designed case made
other design mistakes.
>
>> By reducing the bottom front intake rate, by use of a side
>> intake if not another method, there are lower velocity flow
>> everywhere except into the 'sink. The exhaust fans will
>> exhaust at same rate (providing front intake was sufficient)
>> but a short-loop is created, any air not exhausted into the
>> air most immedate to the exhaust fan will take a longer path
>> till exhausted, and slower.
>
>Short loops are exactly what are needed for zoning the airflows to
>minimize them from intermingling with each other.
Short loops are robbing the lower front area of the case,
unless you then add a front mounted fan which increases
noise level and then reduces the effect of the side duct.
Intermingling is exactly what your side duct causes, because
you prevent the airflow from going in the proven effective
path from bottom front of case towards the rear, by reducing
the flow rate significantly. This is proven fact and was
taken into account and measured when ATX was spec'd.
>Cool the hot stuff
>first with direct outside air and expel it immediately.
Wrong, you have to consider the pressure gradients, to have
suction sufficient enough to intake air into the front of
the chassis unless you add another fan which has drawbacks
as mentioned above. Go ahead and add several addt'l fans if
you like, but if you do that you again eliminate the need
for the side duct by more directly addressing the problem
with your case (if it actually has 15C rise in internal air
temp). Actually, if you case has that high a rise, it would
possibly indicate the problem in airflow that I've already
described.
>
>> Side intake is mostly Intel's attempt to ship cheaper
>> heatsinks with P4, particularly Prescott CPUs.
>
>Wrong. Side intake was to circumvent the ATX spec's poor airflow
>design.
You have supplied zero evidence of this, thus far only
describing a chassis that is overheating, then that the CPU
is overheating as a result unless you add a side duct. You
have still ignored the REST OF THE OVERHEATING PARTS.
A CPU can run at 60C for years, longer than parts like HDDs,
fans, motherboard can.
>
>> The CPU is not the only part that needs cooled
>
>Exactly, so why use the same airflow to cool EVERYTHING?
"Same airflow" means a pseudo-linear path, because this
maximizes flow rate per fan over everything.
You are ignoring a primary detail in system cooling, that
your CPU was not described as overheating and you are not
reporting temps and temp changes of any other parts. This
is a HUGE MISTAKE and quite often why hard drives die.
>ATX is a
>poor design for cooling. Modders knew that for a long time before
>case makers starting adding the extra intake/exhaust ports.
Actually, the vast majority of systems sold and running
today are OEM systems, and they do not have all these
changes the modders made. It may be true that if a
so-called modded had a poor generic case, they needed to
make "some" kind of change to it, and they may not make the
best choice from a airflow:noise ratio perspective, OR they
might be overclocking without a suitable heatink, or as
mentioned several times already, they may not be focusing on
any parts temps except the CPU and system (actually another
chip temp).
BTW, I mod plenty of cases, even early ATX that had no aim
of cooling today's higher heat parts, even overclocking
parts quite a bit as a hobby and do not need to do these
things you imply are important- because I actually meaure
temps of ALL parts that heat up and observe the temp
changes. Most modders don't do this, they just throw a lot
of fans at a situation and end up with a loud system...
certainly louder than Dell et al. OEMs produce.
It is possible to add enough very large, low RPM fans to
offset this and still have low noise:airflow ratio, but then
the expense goes up for quality fans or the maintenance of
these cheap fans increases, and fans mounted on exterior
walls of the chassis always let more noise escape, because
there's nothing to really "escape", they're already facing
the external room.
>
>>>In fact, I've seen CPU and case temperatures
>>>drop in some cases by reversing the backpanel fan so it is an intake
>>>fan rather than an exhaust fan (its normal position) but you need to
>>>test in your own case.
>>
>> This should never be done, it necessarily increases temps of
>> other parts (unless the case was otherwise unusual in it's
>> airflow before this fan was flipped over).
>
>Not if you add MORE venting, like adding a top grill
LOL.
A top grill is almost never a good idea. If the case were
incredibly poorly designed to it was starving for air, or
had a very very poor PSU that was overheating more than
anything else, having the top vent increase airflow might
seem to help, but still robs the lower front quadrant of
airflow, it is a poor choice in resolving the prior choice
of a poor case in general. Such a modder shows they have
made two mistakes, choosing a bad case then choosing a
lesser effective mod and one that may actually reduce
airflow in other parts of the system.
There are plenty of examples of ATX cases that run fine
without these kind of misguided hacks. You are attempting
to suggest ATX is a problem when ATX was not the variable,
rather the other aspects of particularly poor cases were the
variable.
It doesn't really matter if you agree, there are plenty of
examples of ATX cases cooling fine. The most significant
problems with ATX are these two:
1) CPU manufacturer that provides a cheap heatsink that
needs help. The word Prescott comes to mind and the entire
industry has already acknowledged it and praised subsequent
CPUs for not having this known problem.
2) Video cards with very high heat and small heatsinks so
as to not block one or more PCI slots.
In summary, I will repeat what I wrote above as it is key in
your misunderstanding:
You are attempting to suggest ATX is a problem when ATX was
not the variable, rather the other aspects of particularly
poor cases (and system setup) were the variable. When
someone takes on the role of system designer, selects parts
that don't work very well, only then do they have to find a
solution and what you have described is an attempt to
band-aid the problem instead of addressing it directly, then
ignoring the effects on anything but CPU that was not
overheating at all per your description.
I have demonstrated exactly what i have described far too
many times to count, as have the majority of systems running
today made by most OEMs.
Keep in mind that the manufacturer's design of the case
must conform to FCC spurious emission requirements
which preclude opening large holes in the chassis. I
really don't know how the "game machine" manufacturers
get away with their plexiglass sides - unless those sides
have a metal film or the manufacturers' low volume production
exempts them from FCC requirements.
CPU Cooler designs? 