FYI: The PSU can go either fan up or fan down. Sure, fan up is going to suck heat off your graphics cards, but the PSU is fairly heat tolerant. If it overheats (which I doubt), it will shut down. If you're putting the PC on a carpeted floor, mount the PSU with the fan pointing up.
Personally, I have my PC up on a shelf and have the intake fan pointing down so it can suck in cool air.