Help with cooling PC case

[Anth83]

Ok I installed 2 80mm fans in the front of the case blowing air into the pc, there is one on the side panel blowing air on the motherboard.
Now there is room for a 120mm or 80mm in the back. I'm thinking of putting a 120mm in the back. I'm not sure whether to have the fan an exhaust or to have it blowing air IN the case?

The comp is -

Pentium D 805
asus p5ld2
1 gig corsair
160 seagate
Gigabyte 7900GT
antec 400w

It's my brother computer and want to keep it as cool as possible. Gets a little warm in the case.

Would it be better to have it exhaust or not?

[jer888]

how big is the fan blowing air on the motherboard?

seeing as how you already have two intakes, i would put a 120mm as a exhaust

[whubbard]

You want to have more exhaust than intake. So yes you should put a 120 on the back! Also can you put a fan on the top? If you can, do it, and make it exhaust.

[Anth83]

The fan blowing air onto the motherboard is 80mm.

I'm not sure if it has room for a fan at the top, I couldn't see any vents on the top of the case!!

So if i put a 120mm in the back, with the other three 80mm fans as intake, that should keep the whole case pretty cool??

[Chris_Rootes_Wizard]

Yeah, pretty cool.

Front (intake)

Middle (intake)

Back (Exhaust)

And the same from bottom to top if thats how people have it. Because heat rises so theres no need to keep pushing it back down, let it flow happily up and out of the top.