Thread: Case fan question

I ordered me 2 extra 120mm fans for my case cause you can never have to many fans.

Newegg.com - Corsair Carbide Series 500R Black Steel structure with molded ABS plastic accent pieces ATX Mid Tower Computer Case

My case ^

My question is about where I should put the fans. I have two spaces on top of the case, and one on the bottom. The bottom has a few cables bunched up where the fan can go, but I can easily move them to the side of the case.

If I should put both on top, should they both be intake fans, both exhaust fans, or one of each? The back fan spot is always hot where the top cover is, and the front spot is always cool. So I'm wondering if I should use one fan to blow down on my cpu since the front isn't that warm so I assume it won't suck up much heat(especially is the other top fan would too). Both spots are situated right above the cpu(the cpu being in the middle of both). Maybe I'm over thinking this...

Make them exhaust.

negative case pressure means air being pulled through all the gaps in the case because exhaust fans are strong enough to move more CFM then the intake fans. Negative pressure tends to run cooler than positive case pressure. With positive case pressure air is being pushed out of the gaps in the case as well as by exhaust fans because the intake CFM is greater than exhaust. The advantage with positive case pressure is that you can place filters over your intake fans and your case will stay much cleaner.

I run negative to keep it cooler... I just blow my case out with air every so often.

I prefer positive pressure. The main reason is all the air brought into my case will be filtered air.

BL

Negative vs positive is also subjective to how the case is designed as well. Some cases cool better with negative pressure. Some cool better with positive pressure.

Originally Posted by WileECyte

Negative vs positive is also subjective to how the case is designed as well. Some cases cool better with negative pressure. Some cool better with positive pressure.

It seems to have a lot to do with how your fans and case shape and direct air-flow. Sometimes positive pressure can make input fans spin slower and thus cause a slow down in CFM moving through the case and/or in other cases the air just zips through and does not hit the GPU's or CPU adequately. I tested a few cases a few years back and in some cases the difference was nominal, in others it was large, but in all cases negative was cooler. Meh...

Case Fans: Should You Worry About Positive Or Negative Pressure? : How To: Properly Plan And Pick Parts For An Air-Cooled PC, Part 2
This was interesting.


It looks like some companies design cases to be positive air pressure though:
SilverStone Technology Co., Ltd.

It also appears some GPU's benefit from one or the other depending on their exhaust method.

Upon further investigation of the positive and negative thingy(which I knew nothing about till you brought it up) I found out my case is designed for positive pressure. So that means both my fans should be intake correct?

Originally Posted by Adretheon

Upon further investigation of the positive and negative thingy(which I knew nothing about till you brought it up) I found out my case is designed for positive pressure. So that means both my fans should be intake correct?

I can't say for certain without knowing about the fans; remember that your PSU also is an output and many GPU's are as well. Total the CFM of all intake and outake fans (leaving wiggle room for the PSU and GPU since many are hard to rack down CFM for) and the total out should be a bit less than in. Too much positive pressure can slow down fans as they fight to push the air in. if the in/out CFM are near each other the flow is typically greater.