I have a brand new rig and I bought it prebuilt from IBUYPOWER and it worked fine until I changed the cheap Allied 500w PSU to a new Corsair CX550M! Now 90 percent of my games are wrecked unplayable due to GPU usage going from 100% to 0% during play and even in the menu! It is driving me nuts and I tried a normal driver reinstall with clean option also used DDU in normal mode! BUT no help at all! Please try and help me figure out how to fix this! Thanks!