QS (2002) Main Fan

[FdB]

The main (biggest), case fan on the Quicksilver 1 GHz dual is an exhaust fan? (Blows air out of the case, instead of blowing it in?)
Seems odd to me, leaving that little CPU fan to pull air in and blow over the CPU? Just wondering.

[reeskm]

Yes, it's an exhaust fan. If you disassemble the case it will become clearer, but along both plastic panels on each side of the tower and underneath the machine there are air intake holes. So basically it ventilates the entire case from the bottom, through the big 120mm fan, and out the case at the back where there are grill holes for the 120mm fan. This might be counter-intuitive, as you suggest, as this fan is bigger than the CPU fan. However, as long as the exhaust fan pressure and flow is greater than the CPU fan, it won't be a problem at all. If anything, it will make it easier for the CPU fan to do it's job as there will be a slight internal pressure vacuum. This is far better than there being a higher pressure inside the case that the CPU fan has to work hard to push against. Make sense?

This fan doesn't move a lot of air unless the interior of the case gets really warm. It has a built-in thermistor that controls the voltage to the fan. If you room ambient temperature or the internal cards and drives make a lot of heat, it will automatically spin faster and get noisier. I have a small office room and even in the winter when I have several of my machines running at once, the room temperature can climb to 25degC. Then, the exhaust fan on my Quicksilver noticeably spins faster and gets louder.

The power supply fan is also an exhaust fan. You can feel it with your hand.

To prove this, you can take some of those small post it notes used for bookmarking pages and stick them to the power supply and grills at the back of the case. Then you can see the airflow visually and verify that it's working.

[FdB]

Thanks reeskm. Was just putting this QS through the paces after its’ recent purchase. After discovering bad RAM and re-installing OS to a fresh drive, the thing seemed to be getting pret-ty warm without having been challenged all that much. *Not to mention the far too many vacant and open card slots for a nearby "exhaust" fan. So a complete teardown and clean began.

One can remove a lot of built-up dust with an intial blow down but some high-dust concentrations remain [under CPU daughtercard, MOBO, in the fans (main case fan, PSU and CPU fan)], that can only be removed with a much closer effort. If anything, the main fan seemed to be slowing down as it warmed up (I know, strange). Removed small clumps of dust / clogs, from around thermistors (if that’s indeed what they were), on the CPU and main fan. Cleaned all fan blades.

Thermal paste on CPU was totally “baked”. So new paste & reassembly should begin soon… and I now won’t be turning the main case fan around... to blow into the machine. Thanks!

[reeskm]

Yeah, even in a clean environment where you vacuum regularly dust bunnies can build up in this case design.

I also find that they build up behind the 120mm fan and also behind the plastic side panels of the case. They block those air intake vents I mentioned. To fix that, carefully take an allen key and remove the side panels. To completely remove the panel you will have to very carefully push the clips behind the apple logo with your fingers or a tool. The plastic on these things is very old now and prone to the tabs around the logo breaking, so make sure you use a hairdryer or something to heat the plastic first to ease it out. Go slow.

When re-assembling, make sure not to over-tighten the allen keys and go around in a circle in a round-about fashion. Tighten bit by bit and by hand. If you tighten too much, hairline cracks will begin to form around the holes.

If you're careful, you shouldn't have to worry at all. I'm just mentioning this from my experience cause I have now collected 3 QS machines.