Total newbie question

[Buddyroe333]

I know this is probably a reeeeeeaaally stupid question... but which way is a CPU fan supposed to blow the air? Into the heatsink, or out from it? Thanks to everyone who helped me with my last question btw.

 

[smitbret]

As a general rule, down onto it.
-Brett

 

[NurseMSIC]

That's actually a source of some debate....elsewhere other than in the CPU section though.
The (most accepted) answer is you blow down.
I'd still be willing to see a little scientific research though...

Personally i think you should suck up.

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[TheRod]

I will turn your question into another...

Would you better like to have fresh air blown in your face or away from your face when it's too hot???

Fresh air on the heatsink "push" hot air away from the heatsink, it's the best way to get the job done!

--
Would you buy a GPS enabled soap bar?

 

[NurseMSIC]

(Ok, here we go again)

BUT i don't believe that you should blow HOT air onto the CPU which you are trying to cool down
Don't forget, it's the CPU you really want to cool, i couldn't give a stuff about the heatsink as long as it works.

If you suck the air up, then cool air gets drawn up past the CPU first and would help to cool the CPU even more.

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[slvr_phoenix]

Fresh air on the heatsink "push" hot air away from the heatsink, it's the best way to get the job done!

If the heatsink were the only fan device in a PC, you'd probably be right. (Though the design of the heatsink itself could be an important factor as well.)

However one also has to take into consideration the intake and exhaust airflow through the case. Sometimes blowing down works well with a case's airflow. Sometimes it severely impedes the exhaust, in which case having it suck away from the mobo is better.

In truth most of the heatsinks out there are not really designed with a case's airflow in mind. They're designed as if they were existing purely on their own. (Which is rather stupid.)

So the real answer to the question is that it really depends on how the air flows through your case. You have to take it on a 'case' by 'case' basis.

"<i>Yeah, if you treat them like equals, it'll only encourage them to think they <b>ARE</b> your equals.</i>" - Thief from <A HREF="http://www.nuklearpower.com/daily.php?date=030603" target="_new">8-Bit Theater</A>

 

[TheRod]

Wrong!

First the air around the FAN is always cooler than air near the CPU... If not, you have a serious temperature problem in your PC!

For your second point, you are WRONG too! It's a lot easier and eficient to push air into the heatsink than trying to get it out from it...

You can easily test this by using a little piece of paper or some paper tissue... Open your PC case and check how your paper bend with the airflow over your heatsink... Then, put your fan in the opposite direction and check how your paper bend.

And you can compare air volume... The volume of air that can be push in the heatsink is a lot more than air that can be suck from it.

Have you ever see a CAR radiator with a fan that try to blow the air away from the radiator! Never!

Maybe with a specialized ingeniered cooling system it's possible to achieve better cooling by "pushing air away... But if these system were efficient we would see them a lot!

--
Would you buy a GPS enabled soap bar?

 

[confoundicator]

You have to take it on a 'case' by 'case' basis.

*groans*


<font color=blue>Insanity is doing the same thing over and over again and expecting a different result.
-Einstein</font color=blue>

 

[Buddyroe333]

Wow... had no idea this was such a source of debate. I was just scared of putting it on "wrong" and frying my cpu. Thanks for the info guys, much appreciated.

 

[Flinx]

What I'd like to know is why the air is not blow totally out of the case? Couldn't you have a system to vent out the back of the case. Some kind of really big plastic hose like 3"x2" or something.

Do you think that would be more efficient at removing the heat or would some kind of back pressure inhibit airflow?

The loving are the daring!

 

[Syndil]

There are too many variables for a catch-all answer. However Dan at <A HREF="http://www.dansdata.com" target="_new">http://www.dansdata.com</A> has tested quite a few heatsinks. He <A HREF="http://www.dansdata.com/kamakaze.htm" target="_new">claims</A> that heatsinks with shrouded fans tend to work better in the suck configuration, and backs it up with performance tests. So it is not automatically false that any heatsink works better in "blow" mode rather than "suck" mode. My advice, if you really want to go after that extra degree or so of cooling, try both and see which works better for your particular HSF/case. Thats the only way you'll know for sure.

One person suggeted hoses to direct air out the case. However, there is already a similar product that uses hoses to take fresh cool air from outside the case, and blow it directly on the CPU. A very simple, but quite effective idea. Read about it here:

<A HREF="http://www.dansdata.com/badong.htm" target="_new">http://www.dansdata.com/badong.htm</A>

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[Flinx]

I like it!

The loving are the daring!