Orientation of heatsink fan?

[mattrickulater]

Hey there,

Please forgive me if this is a well-versed topic, but a poorly phrased Google search yielded few results.

Is there a consensus as to which way your fan should point/blow with regards to a CPU heatsink? Should it blow air down towards the CPU/mobo or should it blow air back to the rear case exhaust fan?

I'm putting together a new system and I'm curious as to whether I should get something like a Thermalright SI-128 (with a 120mm fan) or a Scythe Mine. Would one or the other increase or decrease the temperature in the case based on orientation alone?

If it helps, I'm looking at an Intel Bad Axe 2 motherboard and a Silverstone TJ-04 case (comes with a 120mm front intake and a 120mm rear exhaust).

Any information for a curious mind would be greatly appreciated!

mattrickulater

 

[enz660hp]

if you are using the si-128, put the fan on so its blowing at the heatsink. If you will use a tower heatsink, arrange the fan on it so that it blows air into the heatsink, aimed at the rear of the case.

 

[bjp999]

The goal is to get the hot air out of the case. I'd definitely aim it at a rear exhaust fan. Blowing the air back towards the MB makes no sense. Some heatsinks suggest "pushing the air", meaning it mounts and blows air across the fins, others suggest "pulling the air", meaning that the fan pulls air across the fins and then blows it out of the case. Check the manufacturors recommendations. You can also have "push pull", meaning there is a fan on both sides, one pushing the air in, and one pulling the air out.

 

[Conky]

If the choice is across the motherboard or out the back, I would take out the back and hopefully towards an exhaust fan.

As far as the push/pull argument across the heatsink goes, most point the fan straight down on to the heatsink fan. The most efficient ones however blow away from the heatsink but they are sleeved to draw the air in across the pins(Alpha's are known for this). If there is no sleeve involved I would point it to blow directly onto the heatsink.