making a fan slot, but where?

[monster.under.thebed]

where should i put a fan (normal size, i dont know the dimensions of it) slot on my case, i was think about putting it either on the top or on the side lower right next to my window,

omg!!!! i just discovers another fan lerking in my room just now!
its a really small old cpu fan from my old pacard bell! now i have 2 fan slots to mod, yay!



ok back to the question where should i put them????

 

[Tengis]

If its an old POS SMALL fan, dont even bother. Buy som 30CFM+ fans and put them above/below your CPU. 80mm or 92mm is what I would go for.