Question Which fans face in? and which ones out?

[ch33r]

So this:

https://www.newegg.ca/p/N82E16811553024?Item=N82E16811553024

is the case I'm getting for my gaming PC next month. It will probably have 5-8 case fans. Which ones face out? and which ones face in? I always been told the ones at the back and top should face out, and the fans at the front should face in. Would that be the best setup?

 

[PC Tailor]

As a general idea:

Cool air enters from the front to bring cool air over your components (including HDD/SSD which is usually at the front) - then as physics textbooks would dictate, the cool air sinks which allows any warm air to force upwards, where they are extracted by exhaust fans at the top or back of the case.

PSU fan should ideally face downwards assuming your case has the appropriate air filter in place, and it will usually exhaust its own warm air directly out the back.

 

[ch33r]

As a general idea:

Cool air enters from the front to bring cool air over your components (including HDD/SSD which is usually at the front) - then as physics textbooks would dictate, the cool air sinks which allows any warm air to force upwards, where they are extracted by exhaust fans at the top or back of the case.

PSU fan should ideally face downwards assuming your case has the appropriate air filter in place, and it will usually exhaust its own warm air directly out the back.

Ok, this is very good. But with the PSU fan facing downwards, wouldn't it just create a massive heat bomb between the PSU and the bottom of the case in which there is zero space between? Or where would the hot air exhaust to?

 

[PC Tailor]

Your case hopefully should have an air filter at this location - where the fan draws cool air from underneath the case (which is why it is best placed on a hard surface as opposed to carpet where it will just suck up dust). It will then typically exhaust the warm air at a right angle out the back of the case as shown in the bottom left of the picture above.

Or as shown here:

If your case does not have this air filter and it just opaque metal, then the PSU fan can face upwards into the case - just this isn't ideal.

 

[ch33r]

Your case hopefully should have an air filter at this location - where the fan draws cool air from underneath the case (which is why it is best placed on a hard surface as opposed to carpet where it will just suck up dust). It will then typically exhaust the warm air at a right angle out the back of the case as shown in the bottom left of the picture above.

Or as shown here:

If your case does not have this air filter and it just opaque metal, then the PSU fan can face upwards into the case - just this isn't ideal.

What difference does it make if its placed on a hard surface, when the bottom of any case is a hard surface anyway? And theres almost no space between that surface and the fan underneath?

 

[PC Tailor]

Effectively the case should have standoffs - which raises it an inch or so from the ground, then the bottom left of the case has a grating that allows the PSU fan to sit on top of it in order to pull air from underneath the case.

It only needs this small amount of space between the chassis and the ground in order to draw this cool air, because theoretically, you should always have cool air below the case as the hot air will not be in this location.

If you case does have this grating / filter, then if you placed it directly above carpet, it would just suck up dust and debris from the carpet that has been embedded in, like a vacuum. Whereas a hard surface is less likely to trap dust and dirt, so the PSU has a "cleaner" source of air (for want of a better phrase).

See how the case has a clearance between the PSU fan and floor below - this works because the case itself has said grating at the bottom left of the case where the fan has the ability to draw air from underneath the case:

 

[ch33r]

I don't even know if my case has that. But here it is:

https://www.newegg.ca/p/N82E16811553024?Item=N82E16811553024

 

[PC Tailor]

Yes it does, it has quite a big bottom air filter designed exactly for this purpose:

https://www.tomshardware.com/reviews/cougar-panzer-max-atx-case,5109.html

Nearly all reputable cases have this for this air flow reason.

 

[ch33r]

Yes it does, it has quite a bit bottom air filter designed exactly for this purpose:

https://www.tomshardware.com/reviews/cougar-panzer-max-atx-case,5109.html

Nearly all reputable cases have this for this air flow reason.

Ooooooook… I see. Very nice. Im going to go through all of that. Thanks for the tip

 

[James1bradley]

I have been using this site for help and ideas and decided to register today. Glad I did as I will now be turning my psu over to the right way......
Incredible site... Thanks