case fan -- intake or exhaust?


Jul 7, 2008
Hi all, I have a new rig with a E8400 (stock clock & cooler) and a 4870.

I have one 120mm fan pulling air in from the front, and the same 120 mm fan set to exhaust at the rear.

My case had a cpu fan hood/chimney thing on it, but i decided to remove it an put a 90mm fan (with filter and screen) it its place. Would it be best if this fan was setup to pull air into the case or expell it?

Right now the side fan is working as an exhaust fan and I've been keeping an eye on temps and everything seems okay the way it is (about 40C at load for the cpu, 75C for the GPU). I'm just curious if i might be better served to having the side case fan blowing onto the GPU.


Feb 26, 2008
Front fan intake, rear fan exhaust, top fan exhaust, and side fan intake. That is how i set up fans on every computer i touch.

Just remember that heat rises. lower fans intake higher fans exhaust.
Agree with stickmans88 in general.

I have a E6400 @ 3.2 w/ 4870.

A couple of notes -
(1) sides and top. will need to try diferent configs
(2) side - If located at top back, I use exshaust and on lower center/front I use intack. Need to try. On my system the 4870 blocks the System temp (I believe it's the north bridge) causing an increase of temp to 39 -> 41 C
(3) top fan, may interfer with CPU air flow ie I have rear 120 by 39 mm) as an exshaust, CPU HSF blows air toward this fan. A top fan may subtract from the air flow across the CPU heatpipes/fines. ( there was a post on this.

Have the colormaster 690 - not totally happy with it. My sligthly modified old case w/PSU at top and no top fan did a better job at cooling.