How to determine exhaust/intake when adding fans?

[fiveohmike]

Hey Guys,

In my other post im debating about what case to get. Any case I decide to get seems to have the options for extra fans. I believe I will stick in as many fans I can but the question is:

How do you determine witch fans are INTAKE vs witch fans are EXHAUST?

Thanks,

Fiveoh---

 

[Lt.Col.Dehler]

any fan can be intake or exhaust. exhausting fans will have their more curved or underside face facing where it is exhausting from. intake fans have their less curved side facing the place t needs to cool
pics of what im talking about:
intake: http://www.hardwarecooling.com/images/SFF21E.gif
exhaust: http://www.thecoolingemporium.co.uk/images/120mm fan.jpg

 

[fantomau]

Some fans have a arrow on the case to show the direction of airflow.

 

[fiveohmike]

I think I may have been misunderstood.

What im asking is wherer do you use intake and exhaust fans? Do exhaust fans only belong at the top of the case? SHould all fans, except for the top fan be exhaust?

Thanks,

Fiveoh---

 

[P£P§!™]

This guide might help you http://www.xoxide.com/computer-cooling.html

its pretty much saying you need a balance of input and output like if you have two fans at the front of your case as intake and you have two fans in the rear you should have them as exhaust

 

[Shambler]

Negative pressure is your friend. E.g. having more exhaust flow than intake flow.

This way the exhaust fans are sucking the air pushed in by the intake fans, as well as from any other non sealed area of your case. Hopefully this will eliminate hot spots, and drop over all temps in general.

I have a different setup however. Extremely loud, but works well with the tried and true Heat Rises.
I bought an Xoxide case with a mesh top, side 250mm fan, front 80 mm, back 120 mm, and set them all for intake. This is more than enough positive pressure from just about all sides to push any and all hot air up the top of the case. Works well since the heat from my vid and cpu naturally rises, may as well push it on out Again, this thing is jet engine loud with regular run of the mill fans... damn mesh top. I will be kicking in a fan controller next week; so when not gaming the 80 and 120 fans will be super low, if not completely off. Set to max the 250mm generates very little noise, yet pushes quite a bit of air.


Almost forgot. The reason why I have my 120mm rear set to intake is: PSU intake is on the inside of the case, directly above my HSF. This way, my rear 120 basically forces cool (ambient) air into the intake fan of the PSU. So yeah, works well. Or, unless I'm mistaken: Even if the outside fan on the PSU sucks in air, kicks out hot air from the inside fan on the PSU: My 120 rear will push that air away form the suction of my HSF. /whew