Fan above CPU cooler; intake or exhaust

[Sulaco]

Hey guys,

Simple question; building a new PC with an aftermarket 140mm fan at the top, located inches from the CPU cooler.
Does intake vs. exhaust really matter? I figured I'd go with exhaust (blow air out) just to help keep dust down, but is there any real world difference? Which would you choose?

(FWIW there's also obviously an exhaust fan at the back of the case)

 

[UsandThem]

You want cool air to come in one side, and blow out the other way. Most people do this by having cool air being pulled in the front of their case, and exhausting out the back and/or the top.

 

[lenjack]

Front in, back out.

 

[Sulaco]

I ended up just putting the fan in the front as an extra intake fan and leaving the top covered.

 

[BonzaiDuck]

Actually, I went against my usual practice with a Corsair C70 Vengeance case, and made two 140mm top-mount fans part of an overall intake configuration.

I also chose to replace the Corsair 120mm fans mounted behind the drive cages with ML120 fans mounted between the chassis and front face plate. The case has a lot of ventilation opportunities, and I will want to block off the bottom ventilation and the vented slot covers.