Silly question about case fans

[X-Caliber]

Hi,

Just a silly question; should I let the fans blow air into the case, or out ?

[Kruzin]

In at the front, out at the back.

[X-Caliber]

Thanks!

-V-

[MultimediaMan]

In my experience, more exhaust flow than intake flow is better for acoustics and temperatures in general: there can and will be exceptions, but a negatively pressurized case generally has less potential for "dead air zones" since every hole in the case EXCEPT the Exhaust becomes an intake of sorts. The bad thing about this type of cooling scheme is that regular case cleaning is a must, even in the cleanest environments.

I gently crumple a sheet of Bounce inside my cases and stick it in a low airflow area of the case and change it monthly: the case stays remarkably cleaner.

[Chris B]

If you have room for fans both on the front and back of your case, do like Kruzin said. If you only have room for fans on either the front OR back then you're gonna get a better effect from blowing air OUT of your case.

I did a little "experimenting" with my own case. Having two fans (at 5 volts) drawing air out of the case (at the back) gave me a significant temperature drop. On a hot summer day after a couple hours gaming my case would feel noticably warmer at the back where the CPU is (this is by just touching the outside of the case with my hand). After adding the fans, I don't feel the temperature difference anymore. My CPU temp dropped 6 degrees celcius.

Adding fans on the front (taking air IN to the case) didn't make much difference. But then again, I don't have much hardware in my case. Only one HDD and one CD-ROM drive.

If you have 'many' disks installed a couple fans on the front would probably be good just to keep them cool.

[GNEP]

If find the fan going out at the back makes a difference to CPU temp. But the on blowing in at the front actually makes quite a difference to the HDD temp.

But the best is the secondary machine - no case fans and only a slow HSF on the CPU. Near silent but it is only a Duron

Always try and get away with as few fans as lets you keep temps reasonable, if only for sanity's sake...

[Admiral]

I took out the two intake fans at the front of my Antec case due to noise issues. I'm left with two at the rear and one on the side that do a good job blowing hot air out.

The best thing is supposed to be a big outtake fan at the top of your case, or so I've heard.

[KvHagedorn]

All this really depends upon your particular situation. My case is positively pressurized, with a 120mm fan at the front, and two 80mm fans at the back blowing air in. I have air conditioner filters in front of the fans to eliminate most of the dust (and might just try that Bounce idea for the micro-fine stuff- thanks MMM!) I have a lot of holes in my case (mostly at the top) for this air to escape through, so what happens is that the increase in number of fans blowing in creates a much higher rate of air exchange inside the case. I can stick my hand in there and it's actually chilly. The floor of the case is downright cold. Now comes the qualifier, though.. I have air conditioning in my house and run it at 70-72 degrees F all the time, so the air being pumped in there is relatively cold. My case is also spacious.. not only deep, but wide as well, and I don't have it full of crap. My hard drives sit in aluminum heat sink drawers in an SCA module with fans blowing onto them directly and sideways, so their contribution to the temperature inside my case is practically nil.

The best thing to do is to just get a really well-designed case. Then you should be alright no matter what. I have found also that using 120mm fans at a somewhat lower rpm does a wonderful job at getting maximum airflow with minimum noise.