Have some questions about fans and cooling

Chickenator

Honorable
Dec 22, 2013
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In my cas i have a back fan, and a front fan which sucks in air. Is it possible for me to have a bottom fan sucking inn air while i have the two fans i mentioned previously? Also, what other combinations is recommended?

When it comes to the PSU fan, should it suck inn air from outside, or from the inside?

Any help with fan placement and cooling related things is really appreciated :)