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.