Originally Posted by dorfman
There are all sorts of opinions on case fan placement.
The most common i've seen is:
1 intake on front, 1 outtake in the back.
Usually the fan in the back are set up higher then the one in the front.
1 intake on the side blowing on the GFX card.
I would have the fan on top being an outtake.
Thats my opinion.
For your set up.
Front : intake
Back : 1 out take
Top : out take
get a fan control, speed up the intake fan and lower the out takes, that should be fine.
This worked fine when PCs were single cores and didn't have the heat issues they have now. Dorfman's suggested setup for the front, back and top fan placements though go more with mainstream performance spec these days.
You want to have a negative pressure case these days - that is, you want more air being exhausted than you blow in. Cases today have so many holes in them to promote air flow that this isn't a problem. Most of the mainstream PCs today do fine with the power supply and a single rear exhaust fan if you know what you're doing. My work PC, servers at home, and rendering system are all negative pressure cases, and they do far better at thermal management than positive pressure cases (more air being blown in than sucked out)
I do concur about the fan control however - a fanbus is a great way to manage airflow in a case.