Originally posted by: busia12
I'm obsessively neat. However, thanks to the lottery that is roommate selection, I get stuck with people who do not share this quality. My girlfriend and I are quite content with the cleanliness of my corner of the room.
Since that is the case then I would recommend some kind of positive pressure system. I don't know if anyone rates cases based on dust resistance, but as long as the case isn't covered with or made out of exposed grills it should not be too hard to seal off, unless you plan on opening it frequently.
I would go for a 120 or 140mm fan intake fan in the front with at least 50% more CFM then your exhaust fan. You need at least one exhaust fan near the CPU otherwise your case temps will get pretty high. It's a lot easier to exhaust hot air near the source than it is to get effective in-flow of cool air.
After you've performed your initial seal-up, power up the computer and take a very fine sheet of tissue paper or something similar and see if you can find any uncontrolled area of the case where air seems to be entering. I would then augment your seal-up job by trying to install another filtered intake fan as close to this leak as possible.
Also, you should consider the quality of your filters. Unless it's a very nice micron/hepa whatever filter, it might just be letting as much dust pass as it catches.