Disabling case fan on a 2002 QS 933

[gert79]

I have been running this machine for a while and like most people i am a bit annoyed by fan noise.

I noticed the case fan is mostly blowing out cold air so i was wondering if it is really needed, air flow wise it is just taking air from the pci and graphics card.

Is it true the case fan is RPM controlled by temperature or load?

I will do some load test with Cinebench and see how hot the cpu cooler gets.

[aBc]

Here’s a suggestion. (With rather ominous undertones.)

Before disabling the fan (and if you’re also running Tiger) download and install Bresink’s Temperature Monitor from Mac Garden. https://macintoshgarden.org/apps/temperature-monitor AND then run it again after disabling the fan just to note the temp differences it might detect after matched sufficient runtimes and loads. I’ve a 933 MHz, a 1.0 DP and a 1.2 GHz Quicksilver. And while the 933 does run the coolest of the three, I think I would acquire a quieter fan replacement rather than just eliminating the “case fan” altogether - if you’re that bothered by the fan noise.

Recently added a faster and much louder CPU fan to the 1.0 GHz DP here, as it was the hottest running of the three. Possible prolonged heat damage coupled with the current scarcity of replacement 933 CPUs should seriously be considered?

Perform a search for “chernobyl” here or review this thread -  http://macos9lives.com/smforum/index.php/topic,4347.msg30216.html#msg30216

[IIO]

the loudest fan in a QS is the one in the PSU, and if you disable that, the PSU will get hotter than a vulcan in under 10 minutes and the machine will automatically shut down.

apart from turning the main fan off you have a few o ther options you might want to consider.

for example buying a replacement fan which is less noisy, halven its speed using resistors, or cuttin out the metal grid of the fan enclosure like someone here did already.

the latter can also be done to the PSU fan - if you dont have cats or little kids in the house or sell the machine to an average idiot later.
 
 
p.s.: oh btw. while it looks it would only affect the PCI area, it of course also helps cooling the CPU heatsink, dont underestimate that (and measure it when you change something)

[IIO]

while OSX is able to spin the fan down when not needed, OS9 is not.

[coachla]

I would suggest running one fan on the CPU at 7 volts using the +5 lead off the PSU instead of the ground, the other lead being the +12 volts.

See my post here:

http://macos9lives.com/smforum/index.php/topic,687.msg44791.html#msg44791

[gert79]

Yesterday i let cinebench 2003 cpu rendering run for an hour but the cpu cooler was only handwarm.

So i created a song in cubase vst 5 that plays lots of notes by vst plugins to create more cpu load.

Still after one hour the cpu cooler was only handwarm.

So i just went for it and unplugged the case fan. Surprise, after ten minutes the machine froze.
Checking by hand the cpu cooler was still handwarm, but the gpu cooler was a lot hotter than before, running a ATI radeon 9000 Pro.

Since i am running on ssd this part will not need additional cooling, i am considering to downgrade to a rage 128 and trying the whole operation again.

Also i will renew the thermal compound between cpu and cooler, probably some heat gets lost there aswell.

[Jacques]

I replaced all the fans in my QS with Noctua ones. However, I made sure the PSU fan still had a good static pressure rating as I reconfigured the PCI case fan to blow air into the case, not extract it. The standard configuration of the fans is a bit odd, you have a small 60mm fan drawing air in over the cpu heatsink, a 120mm fan and 80mm fan drawing air out. There is very little air being drawn into the case and the intake to exhaust ratio seemed very unbalanced. The way the 120mm fan exhausts air is also bound to add noise as it blows air over 2 sets of perforations, resulting in loads of noise. The ‘airbox’ for the 120mm fan with the small 90 degree flow path is bound to push air back into the case.

So my final solution is a 3,000rpm 60mm fan cooling the cpu via cool air intake, more than enough. The gpu gets hot so the 120mm fan blows cool air over the pci slots at 1,200 rpm. The 80mm psu fan extracts at 2,000 rpm to deal with psu heat and residual case heat. I’ve also cut the metal perforated finger guard out of the psu fan extract path as you already have the outer case guard - no need for double protection.

After some prolonged gaming the case is cool, internals are cool and best off all the system is MUCH quieter.

Cpu is 867mhz.

[Knezzen]

Post some pictures!

[Jacques]

Not much to see, here you are.




The little shroud I cut for the CPU heatsink is just there to help direct some of the air down as the Noctua high static fans push air out radially and not as 'direct flow'. 

The large fan over the PCI slots now runs at 8v as I really have very little to cool, apart from a ATI 9200 card. Even as is, it pushes quite a bit of air into the case. So current setup is CPU fan and PCI cage fan = air in, PSU fan = air out.