CPU fan question - which direction?

[sykopath79]

OK, this question has nagged my brain for years now and I've never figured out the answer. But seeing as I'm about to throw a 2500+ Barton in my system and overclock it as high as possible with air cooling (Thermalright SLK-900A and 80mm fan), I would like to know what the general consensus is.

Which fan orientation is best for cooling?

1. fan blowing downward onto the heatsink, pushing air across the fins, or
2. fan blowing upward away from the heatsink, pulling air off of the heatsink

Please let me know what you think, need answers ASAP so I can get started upgrading.

 

[MichaelD]

Number 1.

The SLK900 is the best HS out there right now. Good purchase. How many CFMs is that 80mm fan? If it's at least 30CFM, you should be able to OC the snot out of that Barton.

 

[Davegod]

def #1.

Only a few heatsinks are better with it pulling air up through it, usually pin (rather than fin) designs.

 

[TrailerParkKing]

when i got my slk-900 i e-mailed thermalright and they said they recoomend blowing donw on the HS

 

[Sid59]

if you're gonna get the slk900 .. get a 92mm fan.

 

[Sid59]

wow .. so i should change the direction my fan goes on my slk800A ? better to pump air in or suck air out?

 

[sykopath79]

Originally posted by: MichaelD
Number 1. The SLK900 is the best HS out there right now. Good purchase. How many CFMs is that 80mm fan? If it's at least 30CFM, you should be able to OC the snot out of that Barton.

I loved the SK6 I was using with my T-bird, so choosing another Thermalright 'sink was an easy decision.

 

[TrailerParkKing]

Sid,

I believe that they reccomend that for the 800's as well.

I tried a delta 92mm(58 cfm) fan on my SLK-900 and I got slightly higher temps than using my 50 cfm Sunon. I also tried running an 87 CFM 120mm diagonally on the hsf. it look HUGE... kinda cool but again i was running a few degrees hotter than with the sunon.

Others may have had good luck with the 92mm's or the 120's but i am sticking with my 80mm sunon because all around temps are better.

enjoy the SLK-900, they do rock!!!!

Just a side note, i only rund 3 degrees hotter under load than my roommate who runs water.