I ordered a new psu (corsair TX650) and video card (xfx radeon 6870), and newegg decided to send me a free 80mm case fan (40 CFM). My gpu temps are a bit high for my liking, with 45C idle and 90C max (furmark), so I've decided to put the case fan is - not sure where, though.
Right now, there are no dedicated case fans - just a pretty big cpu heatsink fan (avg. 1200 RPM) intaking air from the side, the gpu fans, and the psu 120mm fan (which pulls air up and out the back).
For what I've read, the best place for the new fan is rear exhaust. Problem is, this would put it right below the psu fan (which pulls air up and out the back of the case). I'm concerned that placing an exhaust fan right below the psu will hinder its ability to draw air up and out...
So - should I be concerned about airflow conflict if I mount it as a rear exhaust?
The rear mounted fan would actually aid the PSU fan in pulling more cool air into you case from the outside world through any cracks you have available. Personally I don't think it will matter. More air flow is more air flow. Your temps will come down.
One other thing, furmark is a stress test. Your temps won't normally be that high while gaming.