Very nice setup, I have a question as to how you have the RP452x2 setup. I have the rev 1.3 and I cant get my system to work. Are you planning on using the loopback kit? if so are you using the included acrylic piece and are you removing the long plug? I will definitely want to know what trick you used to get your system to bleed properly.
Lastly for the 580gtx. Mine came with a diagram that showed the 6 pin power connector lacking the top center pin. All my pci-e cables have the full 6 pin setup, and the only adapter my card supplied was a molex adapter with the proper pin heading. Did you have the same diagram I wonder?