Shuttle XPC SN85G4 PSU

What is the best PSU that I can put inside my Shuttle XPC SN85G4 that has the power to run the newest graphics cards? I am currently stuck with the default 240W power supply. I can run the x800 Pro and XT probably but not the new Geforces.

I believe that Shuttle XPC's use standard 1U server PSUs. Fortron is a good company and makes some of those, you can buy them here. I reccomend getting the 350 watt version, though 300 watts would probably be fine.

none of those are SFF PSUs.