geek, wouldn't it be better to draw air from the outside of the case instead of from the GPU-heated inside (with the fan facing up)?
Your suggesting drawing fresh air into the psu from outside the case and pusing it right back out the back of the psu, that would make no sense. That would be great for cooling your psu though. lol
You want to draw hot air from inside the pc, out the back of the power supply and out of the case. The fresh cool air comes from your intake fans and the front of the case. This cycle is what keeps the entire pc cool.