On Mon, 11 Jul 2005 20:33:06 -0400, "Frank"
<Frank@hotmail.com> wrote:

>Just want to know if anyone has one of these 100+ cfm sunon or panaflo
>fans.

I have both, have had/used/sold/etc several models and
speeds.



>I'd like to know how loud exactly they can be a full speed and how
>quite and performing they can be at minimum revs.

Which model, size, flow rate?
Ideally you'd use the largest diameter and thickest fan the
space allows. "Full speed" is relative to the particular
model. If your concern is noise (as it should be, there is
no need for max possible speed out of a large fan except in
some kind of non-traditional system or extreme environment),
then don't choose the fastest speed model in any give
family. For example with the Panaflos, there's "L", "M",
"H" and even higher in some models. Seldom is anything
faster than "M" needed in a larger fan, and usually "L" is
sufficient.




>My application is to cool a watercooling HW Labs xtreme radiator.

You seem to have left out a vital detail- What size fan it
can accept.

This can be signficant for the question posed in particular
because Sunon's 120 x 38 mm fans don't respond well at all
to voltage reduction. Far sooner than many, they begin to
have too little torque to overcome the magnet and make a
pulsing sound and far less linear RPM (& flow) reduction
with no addditional noise reduction, even introduction of a
new noise from the irregular RPM rate.


>I went
>watercooling to have a dead silent pc and not to overclock in general. So
>the fan would always be at minimum revs and maybe turn it off if temps are
>not too high. But when gaming, i'd like to have full power and noise would
>be less of a factor but still, I don't want a vaccum cleaner in my pc. I've
>heard these fans a screaming loud.
>Just want real life opinions about these. Other fan suggestions are welcomed
>too.

The key to quiet is to keep fans at minimal speeds. If one
fan at minimal speed isn't sufficient while gaming, add
another fan, turning the 2nd fan on when heat rises.
However, with an optimal fan strategy it isn't even
necessary to control fans turning on/off or changing RPM at
all. Remember that it is not at all necessary for a PC to
always remain at a constant temperature, only to stay under
your target temp. That's not advice against implementing a
fan control of some sort, only that it isn't necessary and
depending on the control method, could be less reliable in
the longer term.

Panaflo is your best bet. Papst are good too but pricy.
This assumes vertical orientation of the fan, for
non-vertical (horizontal or ANY other non-vertical angle)
you may want dual ball-bearing rather than sleeve fans to
prolong their lifespan in these orientations.

Everyone has their own idea of what "quiet enough" is. It
can vary based on chassis quality, mounting method for
fan(s), and system placement in addition to other factors.
Point being, some might find a 120x38mm "M" Panaflo quiet
enough when undervolted. Most would find it louder than
they "like" at full speed. Remember that you don't
necessarily have to choose between the low-speed for idle
and full speed, but could just as well choose between one
undervolted speed and a higher undervolted speed during
(gaming or whatever).

This potential for never running at full speed unless you
really need to, makes an "M" speed more flexible than "L".
L speed is more tailored towards low noise though, and is
sufficient for most systems especially if the case intake is
large enough and mostly unobsstructed. Optimally more than
one "L" speed would be used for the most control at lowest
noise but if your case doesn't allow it, that may be the
justification for the single "M" speed fan with more
aggressive RPM throttling.

Note also that to get fans to spin-up yet still be at lowest
voltage, it helps to use a control method that limits
voltage rather than current. For example, a simple 15 cent
inline resistor does quite well for typical undervoltage
needs, but to get a fan working reliably at lowest voltage,
use series-diodes or perhaps one of the common integrated
regulator chips such as a LM317. Using something like an
LM317, you can also put a thermal sensor into the circuit or
control it with a POT.

While there are other fancier PWM based front-panel fan
controllers, many produce a whining sound from their
inductors, and those I've tried do not allow fan spin-up at
as low a voltage, therefore higher final rotational speed.

Some radiators place the fan a bit too close, producing
additional turbulent noise. I'm not familiar with the one
you mentioned but if that becomes an issue you might
consider finding or making a shim to place the fan an
additional cm away from the radiator. This will reduce the
flow rate through the radiator, but even so, the slightly
higher RPM needed to produce same flow rate can result in
lower noise than having the fan too close- which again I"m
not certain about on that particular radiator.