Regarding the GPUs... are you looking to get the reference cards, 3rd party branded ones or it doesn't matter?

As for the PSU, I can get the SERVER PSUs available in 750W, 1000W, 1200W, 1600W + (i.e. Hot swap type blade connection that can be used with a breakout board populated with 6pin PCIe connectors).

Or would you prefer consumer grade (i.e. desktop style square boxed)?

If its the latter (consumer grade) I can get Antec, Cooler Master, EVGA, Seasonic, Thermaltake etc.

Let me know if you have a preference