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Should the fan blow or suck air?

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Pla

Member
Joined
Apr 24, 2002
Location
San Francisco, CA
The airflow direction through the rad will be the same.
Which way is more efficient - blow or suck air?
Any observations with your system?
The only think I can think of are these 2:

1) The air flow may be more in one of the cases.
2) The air should be cooler when sucking it because its presure is lower.

Anybody tried? Any differences in themperature?
Thanks for any comments.
 

SkiFletch

Member
Joined
Jun 24, 2002
Location
Crotchfester (aka rochester), NY
best way to do it is to try and use outside ambient air to cool it, instead of case air. whether its blow vs suck usually only makes a .5c difference in temps. provided the air always comes from ambient, it shouldnt matter either way
 
OP
P

Pla

Member
Joined
Apr 24, 2002
Location
San Francisco, CA
Thanks for the advises.
My rad is outside the case so the air is optimal. I'll place the fan to suck air and will post the result later.
Thanks.
 
OP
P

Pla

Member
Joined
Apr 24, 2002
Location
San Francisco, CA
It gave me 2C lower when the fan was sucking. This is too much difference.
Somehow the airflow is a little better - the RPMs of the fan are lower for the same voltage so the airflow must be higher. (If I cover the fan the RPMs go higher and the airflow is 0.)
It may be just result of less dust...
 

Toysrme

Member
Joined
Nov 12, 2001
It shouldn't make much of a difference if it's outside the case. Either way the fan will have to fight the heater core to suck/blow air through it.

If it's in the case, then I would take it as a case by case basis (no pun intended)

On the one hand the radiator will run cooler from outside air pulled in giving you a better cpu temp, but higher case temp. (assuming you have adequate case airflow already)
However if you blow air out your CPU temp will be greater, but if you don't have enough exhaust fans to begin with then your case temp will lower.

-Toysrme
 

JFettig

Hey! I showered! Senior
Joined
Jan 5, 2002
Location
MN
I did a simple test a while back, an 80watt peltier, and a heatercore, I tested with a fan blowing with a shroud, without a shroud and sucking with a shroud, blowing and sucking were exactly the same and without the shroud it was up a few degrees