Intake/Outtake Fan Question

[mike_j_johnson]

I cant believe I am asking this...

Please correct me if I am wrong:

Front case fan = intake??

Rear case fan = outtake??

CPU fan blows air away from the CPU or towards the CPU????

 

[omz]

it depends on the orientation of the case fans but yes..i believe all that is true
front = intake
rear = exhaust
cpu = exhaust

 

[Lsv]

i've got the opposite for case fans, my front and side are exhaust but rear is intake, it draws cold air over the hsf of my cpu and also into the psu which is very close to cool that aswell

 

[mike_j_johnson]

I ask because a friend of mine swears that the CPU fan is supposed to blow air onto the CPU. I thought it was opposite.

So I am starting to second guess my 10 yrs of computer knowledge in this area lol.

 

[tsuehpsyde]

I ask because a friend of mine swears that the CPU fan is supposed to blow air onto the CPU. I thought it was opposite.

So I am starting to second guess my 10 yrs of computer knowledge in this area lol.

It goes both ways, really. All in how you look at it.

Technically, it's more efficient to blow away from the CPU, then have that air ducted out of the case...so it's always moving ambient case air (not recycled from the heatsink air) thru the sinks. But, most aftermarket HSF blow onto the CPU...the XP-120 can go either way, and is designed to go either up or down, fan wise.

So really, there is no definitive answer for the CPU question (I consider blowing air away from the sinks to be "correct", but it's not always the most efficient for certain CPUs/configurations...I believe my Athlon64 X2 cooler blows down), but yes the front of your case should be intake, and the back should be exhaust.

 

[p0intblank]

I have a tornado 80mm fan on my cpu heatsink blowing air onto my cpu and my temps go from 78F to 97F, idle to load, respectively. So I don't see any reason to turn the fan around. And thats at low to mid fan speed, I rarely have it at full speed.

 

[dlion]

Hmmm, In my opinion, here is how you should set it up.... Ideally you would have an exahust fan high on the rear of the case (or even on top), intake fan low on the front of the case, and the cpu fan blowing down towards the cpu. My reasoning is this: Hot air rises, so most of the hot air will reside atop the case, hence blowing it out from the top/rear is sensical. Cool air is denser, so an intake fan would be at the bottom, pulling in the coolest possible air. As for the cpu fan, I have have tried both ways, and in all the setups (that I have tried), its cooler blowing on the cpu instead of away. I think a good real life analogy would be a box fan. If you put your face behind a box fan, the air being wooshed by cools you, but not nearly as much having the air blowing directly on you.

 

[nst6563]

sorry..this is OT...but I just have to get this off my chest.

Intake is fine. Outtakes are normally found at the end of movies when the actors screwed up. Exhausts are just that...exhausts...they expel.


On topic...try each configuration for yourself. This is the best method to find out for yourself what provides the best results. It's time consuming, and much easier if someone else just says what to do, but use those as suggestions to go by.

 

[dlion]

sorry..this is OT...but I just have to get this off my chest.

Intake is fine. Outtakes are normally found at the end of movies when the actors screwed up. .

LOL

 

[velusip]

In most standard cases the air intake is at the front, low on the case and exaust is right below the psu at the back. This works fine in most scenarios.

The most standard of HS fan blows onto the processor, but some blow across heat pipes or radiators. Having the fan suck air away would not be as effective as this would reduce the level of turbulence caused over the HS metal.

Overall you want to get as close to a straight line of wind moving through your case and as little turbulence or "recycled air" as possible.