ComputerBB

i recently built a new amd 64 bit 3400+ w/ motherboard and radeon x800 pci express, but i decided to use an old 300 watt power supply. it ran fine until the other day while i was playing a game, the power supply died. i bought a new 450 watt power supply and put it in, and everything worked fine, exept for one thing. when i try to play any type of game, the game run at half the speed that it's supposed to. i'm not talking about half the fps, it's like the game is running in slow motion. i've already gone and checked all the settings that i know of, and all the settings appear to be normal. any help is appreciated.