Rear case fan direction?

[Tac134]

So my CPU heat sink currently has the fan blowing out to the rear fan which also blows out. I had a friend tell me to point my rear fan to blow in and that would make the air rise to my top fans. Currently I idle at 25C and 70C on load, with a 3570k @ 4.3ghz. I know these temperatures are completely fine, but I'm just wondering if what he said is true. I've done a little bit of research but haven't found any concrete argument for having the fan blow in. Will it help my airflow in my case?

Related Specs:

i5-3570k @ 4.3ghz
Hyper 212 evo
Rear fan - 120mm NZXT
Top fans - 2 140mm NZXT
Phantom 410 mid tower

 

[Quadacon]

the underneath of the fan always point onto the heatsink, air blows on to the heatsink

 

[Kjwinden]

You want airflow to go one way in a system. Fans in the front pulling air in, while all fans in the back pushing air out (with your PSU in the back pushing down and out and any fans on top in back pushing up and out). If you have fans blowing in different directions...the physics is too much to explain..but its bad. Just have a unidirectional airflow.

 

[Heironious]

I had a friend tell me to point my rear fan to blow in

Found half the problem right there.

 

[jsc]

Basically, front in; back and top out; side generally in but you need to test.

In my Antec 900 cases, adding a side fan (either in or out) does not help internal temps.

 

[Tac134]

You want airflow to go one way in a system. Fans in the front pulling air in, while all fans in the back pushing air out (with your PSU in the back pushing down and out and any fans on top in back pushing up and out). If you have fans blowing in different directions...the physics is too much to explain..but its bad. Just have a unidirectional airflow.

I wasn't going to bother unless one of you guys said it was a good idea. All my fans are blowing up and out, which I already though was the best way to go.

Thanks.

 

[Tac134]

Found half the problem right there.

Right? Usually when he tries to help me I blow it off because it doesn't make sense, but I wasn't sure if I was right this time.

 

[Tac134]

Best answer selected by Tac134.