No boards support true PCI 3.0 to start off. You would need an Ivy Bridge chip to do that, which will replace Sandy Bridge, if you want upgradability and SLI etc. The P67 Pro3 was not a very good choice, get the Asrock Extreme3 Gen3 Z68, that'll give you the biggest bang for the buck in terms of upgradability.
As for the PSU, it depends again. Do you plan to SLI or CF? If not the 520C would be perfectly fine, if you do then get something above 650w+ that's efficiency is good.