If I was to setup the maximum amount of GPU's within a mining rig that's PSU is over 1200 watts how many cards could it potentially support?
6 AMD 7950s can easily run on a 1500watt PSU, but since 1500 watt PSU's are the same price as a 1600 watt, might as well get the extra headroom. Example: http://www.coinminingrigs.com/how-to-build-a-6-gpu-mining-rig/
You'd want to under-volt the cards anyway to save on your power bill as well as put less strain on your PSU. Use a gold rated PSU and please don't mine Bitcoins with a setup like this. You won't mine anything worth talking about. Scrypt based alt-currencies are where it's at with GPU miners these days.
