I know the Prescott chip gets very hot but I have a Northwood, and I
know they're cooler. I have a rear case fan and the hardware readings
in the BIOS say the case temperature is 85°F and the processor
temperature is 105°F. Even after an hour or so the temps are the same.
I want to cut down on noise and a lot of it comes from the case fan.
The fan itself is quiet but the air being blown out the back of the
case creates noise. Would disconnecting the case fan have much impact
on the temperature? The computer is in an environment where the room
temperature never goes above 74°F.
Thanks
Without a case fan of some sort (PSU fan, front intake fan,
rear exhaust fan), the inside of the computer will get quite warm.
You would be relying on cooling through the walls of the computer
case. Not too effective, unless well engineered. Your hard drive
would be most at risk, if you disable all case fans. Followed
by the PSU packing it in, if the PSU fan was absent. This is
an example of a well engineered fanless system.
Fanless Ultra Powerhouse PC (Zalman TNN 500AF computer case)
http://www.silentpcreview.com/article301-page2.html
Here, heatpipes transport the heat, into the side panel with cooling
fins on it. Without the heatpipes, there would be virtually no
effective conduction to speak of.
http://www.silentpcreview.com/files/images/epcn-tnn500/epcn5.jpg
What you could do, is use one of these to adjust the voltage to
your fan. This one apparently goes from 7V to 12V, but has no
"off" position. The inductor coils tells you, it uses a switching
design, which means the fan controller itself should not waste a
lot of power. But read the reviews, to see if there are any other
issues to know about. (There are cheaper ways to do this, but this
is pretty convenient.)
http://www.newegg.com/Product/CustratingReview.asp?item=N82E16813999504
Once you slow the fan down, then you have to watch the case temps.
Test with either 3DMark looping (if you have a hot video card), or
use Prime95 Torture Test. What you are watching for, is the case
air temp getting too hot for the hard drive. The processor has its
own protection mechanisms, and if it gets too hot, it will slot its
execution rate, to control the heat. Not so with the hard drive.
I have a large fan on the back of my P4 computer, and it is already
down to 7V operation. But because the fan is a monster to begin with
(it is a 120x120x37.5), I didn't expect it to be silent, even at 7V.
Fans come in various CFM ratings, generally four different ratings
per size. Selecting a fan that runs at 1200 RPM, for example, would
probably mean that no voltage reduction would be necessary. You can
start with a "high" or "ultra" fan and reduce the voltage, or
use a "low" or "medium" and run it at the full 12V.
On this page, fans with 12L, 12M, 12H, 12U (part of the Panasonic part
number) stand for fans running from 12V, and being low, medium, high,
and ultra CFM (cubic feet per minute) rated. You select your fan for
the expected heat load in the case. The "dBa" rating is some kind of
acoustic rating (which no two manufacturers do quite the same way).
Maybe 30 dBa would be audible, or maybe some other noise source in
the computer would be louder than that.
http://dkc3.digikey.com/PDF/T063/1788.pdf
This article gives an equation for how much CFM is needed for a
given total amount of heat in watts. Obviously, when multiple fans
are at work, they can aid or hinder one another, and with multiple
fans, you need more math (and tables/curves) to figure out how
many CFM you really get.
http://web.archive.org/web/20040201223228/http://www.chassis-plans.com/cooling_and_noise.html
One of the limitations of the average computer case, is only having
room for one exhaust fan. Notice that Apple computer has successfully
used "zone" cooling for some of their products. The computer case is
divided up into compartments, and each compartment has its own, slow
speed fan. The idea is to have a "wall" of slowly moving air, to
carry the heat from the case. There are some PC cases that use this
principle. So you could search for a better designed case, in order
to balance noise versus cooling effectiveness (and at least a case
like that, would be cheaper than buying a TNN 500AF). This is an
example I picked at random - there may be better cases than this:
( Antec P180, where power supply fits in lower bay. The hard drive bay
to the right of it, gets the cool air as it enters the lower section
of the computer. The fan in the middle, then moves the air out through
the PSU. With this one, the PSU must have long enough cables, to reach
the rest of the computer. Some cheaper Fortron PSU wires are too short. )
http://images10.newegg.com/NeweggImage/productimage/11-129-154-37.jpg
Paul
