Heatsink fan direction

[rampantandroid]

Looked to see if I could find a definitive answer on Hard and found none; what's the verdict on heatsinks like the TRUE120 and Megahalems in a case where both the top and back fans blow hot air out (like the HAF932):

Have the heatsink blow hot air UP or horizontally out the back? Does it matter much? Will motherboard cooling to better one way or the other?

Thanks!
RA

 

[Cruiza]

I think I've read that the heatpipes work slightly better when the HSF is situated so that the fan blows vertically. If you have the EVGA X58 SLI (E758) board, though, you may want to have your CPU fan blow horizontally so the VREG heatsink gets some air.

 

[vagabond142]

It really depends on what heatsink you're using, as well as the motherboard. You always want to have your mobo receiving some type of passive cooling, especially if overclocking. That said, a HSF will always work SLIGHTLY better (emphasis on the slightly) in a South to North blow direction versus a East to West blow direction, if using only one fan. This is due to simply thermodynamics, ie hot air rises naturally.

HOWEVER...

Inside a computer case there are a variety of different pressure situations that can exist, and air is constantly in motion, even if you have a fanless case that is entirely passively cooled (think one of those Zalman cases that are just gigantic heatsinks).

If you want the absolute best cooling possible, no matter the orientation, then having a large surface area with a direct, pressurized flow of air will be your best bet. This is accomplished via a configuration known as "Push-Pull." You have one fan on the front of your heatsink, blowing into the sink itself, aka the standard tower style like a TRUE120, Mugen 2 Rev B, CNPS10X, etc. However, most, if not all, of these coolers have bracket holes to let you put on a SECOND fan, on the "back" of the heatsink, ie opposite the "push" fan, which blows air into the fins of the heatsink, "pulling" the air from the front fan out the back of the fins.