cpu airflow

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YO_KID37

YO_KID37

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Jan 15, 2006
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I've got 2 Extra ducted fans on my case, and was blowing in, but i've reversed them and am blowing out the ducted type and am getting lower temps from about 40c idle to 33c idle now. yay 6c lower and about 12c lower when running from 48c to 37c~ now yay!!
 
SidVicious

SidVicious

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ive already made a post about this so ill ask here. is blowing air onto the cpu better than sucking air away from it. obviousyl they blow onto them but is it better than taking the hot air away?
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Yes, blowing cold air toward the CPU increase the temperature delta between the hottest part of the heatsink and the surrounding air. The hot air is then pushed away from the heatsink.

Sucking air out would'nt work since the fan would be sucking air from the coldest part of the heatsink, found at the tip of the heatsink fins.
 
S

SteveO

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Dec 21, 2001
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The fan on a heatsink pulls the heat from the cpu/heatsink, the fan its self generates heat. Hold your hand over the fan and you will understand.
 
uber_g

uber_g

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image0087mr.jpg



air from the top moves down


-my finger showing the direction of air flow


i hate my phone
 
S

SteveO

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A stock fan thats in a prebuilt computer always blows away from cpu. sid is right though i dont know alot about forced convection. but then i thought all convection cooling is forced. Aluminum distributes its temperature fairly over all its surfaces. If a fan and heatsink is doing its job well it will draw or blow cool air over all surfaces of the heatsink. A fan can suck as well as blow.
 
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SteveO

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so are you saying if i had bought this exact same specs prebuilt they would have reversed the fan on my heatsink?
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That would depend on the person assembling it i would think. I know HP,IBM,and Apple all blow away from heatsink. And i am sure they know something about computers
 
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SpeedballTrix

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If you have a rear exit fan right next to your CPU than you should reverse the fan to pull air away from the CPU so that the rear exit fan can pick it up.
Otherwise you have the larger rear fan and the smaller CPU fan fighting for the same air.
Who do you think will win?
Not you.
 
Grimmy

Grimmy

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(scratches head and wonders where the hell did that come from).

oh and it would be gone FROM suck to blow not to.

that'll teach ye not to make a mockery of this thread :twisted:
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Hey... its been awhile since I saw Space Balls.

Nice to see I wasn't the only one who watched it. :p
 
ZOldDude

ZOldDude

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Apr 22, 2006
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does a stock cpu fan blows air towrds heatsink or sucks air out from heatsink?
im using amd 64 3000
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Most that I have seen blow the air down....but the hotest part of a HS is under the center of the fans hub.
Drawing the air up has that same issue.

They make plastic stand offs that hold your fan away from your HS and improves the air flow to the center of the HS.

On all my builds I have the fan blowing down onto the HS....and run a tube from the side case to just above the fan. This draws cold outside air to feed the HSF rather than the warm air inside the case.

Useing this method drops the CPU temps as much as 30 F ( 20+ C) in my builds useing the stock cooling that comes with the cpu's and does so without the use of an extra fan.

With proper air flow engineering I am able to do about the same as a non-chilled water cooling system and only use two case fans (cool air IN over hot parts,hot air OUT....all in a dirrct line).

Z
 
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