direction of CPU fan

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very basic question. is it better to have my CPU fan's blowing into the CPU or blowing away (so that the hot air is being extracted out)? thanks.
 
i always blow in, and it seems to work quite well. but if you want super cooling, get two fans, put one on one side blowing in and another on the other side blowing out (you need a huge heatsink for this, though.)

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Satan Clara...... 'Nuff said.
 
griz is right. blowing cool air onto the cpu works much better than sucking away hot air.
 
I disagree with the others. I have my CPU fan sucking the hot air away form my CPU. The way my case is set up it has a large exhaust duct and fan above my CPU cooler. And it seemed like to 2 fans were fighting each other before. I checked the temps and they were like 1 degree lower with my fan blowing away form the CPU. I think it really depends on your setup as to which is best.
Good luck & Cya
 
I don't think the fact of the fan blowing one way over another is a simple question of airflow, but more so a question of heatsink design. The Copper Hedgehog and Alpha PAL6035 utilize shrounds around the top of the heatsink covering part of the heatsink using a fan pulling air from the heatsink and blowing outwards. All other heatsinks I have used that do not have a shroud usually have the fan blowing on the heatsink. The Alpha PAL6035 cools the best for me so far with the least amount of noise due to the Sunon 30cfm fan I used, it blows outwards, not in. This setup keeps my 1.2Ghz at 1.37Ghz cool and under 50C under full load.
 
well that's because the exhast fan wasn't giving any air to the CPU fan. If you would have turned that exhaust fan around, you will get much better performance.

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Satan Clara...... 'Nuff said.
 
Isn’t that the point of the “exhaust” fan. To exhaust the hot air from the CPU out.
I had it setup the other way but didn’t like the idea of the hot CPU air circulating throughout the whole case.
Cya
 
The following faq/answer came directly from globalwins site tech info questions. I guess this says it all!

Hot air rises from the CPU, How is the air flow direction of a cooler better? Suck above or blow down to heatsink (CPU)?

When you feel so damn hot in summer, do you prefer to have the fan sucked or blown to you directly?
 
In general it is has to be better to blow towards your heat sink, as you want to induce the maximum possible turbulence and velocity in the flow in order to carry the heat away from the heatsink surface.
Whichever direction you blow in you are going to get turbulent flow because of the sharp/square edges on the heatsink elements, but blowing will give you more.

Now, there may be some cases where you want to avoid blowing, possibly because that would be supplying warmer air than sucking because of the relative location of vents, power supplies etc., but start with the assumption that blow is better.
 
in my heatsink the fins are like airplane wings so the air flows better, i dont have to worry about that stuff you were talking about.

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Satan Clara...... 'Nuff said.
 
I did see one on the net (inflowdirect.com) that had a fan on each side of the heatsink one pushing, one pulling and looked well made but at $26 bucks it has a lot of old reliables in its price range it has to compete against.
 
Forget all the opinions and theories, just try it both ways.
Many fans can be reversed without even removing the processor or heatsink. I tried both ways with my PAL6035 and found 5c less aimed away from the CPU.

It is not that these guys don't know their stuff. The problem is that it depends on the case and fan arangement etc. What is better in one setup may not be as good in another. Good luck.
 
lol, so what is it? suck or blow?
heh would i be a better idea to put the fan on side of tower positioned to blow onto the CPU(& its fan) and another fan blowing out the air, (where would i put the second one?) on top?


<font color=red><b>-RocKo</b></font color=red> 😎
 
Thats how I have my fans set up now. I have one blowing in at the bottom front directed into one on the side blowing into my heatsink fan which is also blowing which is right under the power supply fan which is sucking everything out at the top. I would not want to use a draw hs/fan when I go to a slot one adapter because it would blow the hot air at very close range right into video card. So I think it really depends on your case setup and space where you can put one. I have thought about adding a slot fan or one of the small squirrell cage blowers from radio shack attached to the top back if I find I need more. I think the key is to position your air flow so that it is a flow of intake, cooling, and exhaust in a progressive pattern from botton front to top back rather than fans blowing all over the place maybe working against each other or blowing the same air back and forth.
 
actually I thought it went like this:

"Drew Carey defies the laws of physics by proving that you can suck and blow at the same time!"

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"648kb is all the space anyone would ever need!"

Bill Gates, 1980s
 
Either way will work, since you are moving air around the heatsink fins and moving the heat. But sucking the heat away from the heatsink is generally considered more efficient than blowing the heat into it.

As far as the heat rising issue goes, that really won't matter much since most cases have the motherboard and CPU mounted vertically instead of horizontally. When the heat rises it just goes up the side of the heatsink.
 
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