So I'm going to run a GeForce 6600GT on an HP Pavilion 775e. I'd like to replace the Power Supply (as the one that came with it is only 200W). However, the supply unit looks small. Does anyone know if HP usees weird PS units? I got a XION Simply 400W XON-400X ATX 400W Power Supply and the width is ok, but it is so long it butts up against my CD drive. There is no room for the CD cables, and the vents on the back of the power supply are completely blocked. I'm guessing I need a shorter power supply, but often dimensions are not listed in the specs. Any suggestions?