I have a Coolermaster HAF 912, and it supports 2 front 120mm fans, 1 side fan, 2 top fans and 1 rear.
Currently I have
3 Antec Tricools, has 3 settings, which have the ratings of
Low 1200 39
Med 1400 56
High 1600 79
3 CM Stock Case fans,
And 1 Kingwin
I have a Hyper 212+ Heatsink, which has a rating of Rpm 600-2000, CFM 21.2-76.8
Currently this is mounted facing upwards.
I forget the exact layout but I believe I have the 1 antec on the side intake at low, 2 in the front intake on med, and 2 stocks on the top out and 1 stock on back out.
I set this up around July and seemed fine.
I had to go in to check something earlier and im talking crazy dust in there.
I vaguely recall something I believe positive pressure in minimizes dust, hence i put the fronts on medium, etc.
Is this proper? I have 2 sli geforce gtx 260s and the sides of them are covered. seems the only thing clean are the fins on the heatsink.
Well, dust is INEVITABLE, no matter what you do. i clean my case out once a month, just to keep optimal airflow and fan performance. I would say that higher fan speeds though would be best, as a more direct, high speed airflow would direct more dust enterring the case out of it. instead of giving it a chance to settle.