PSU causing drop in X800 XT performance?

[Sect. Eight]

Picked up a ATi X800 XT AIW a couple weeks ago and have been very dissapointed in my FPS thus far. Seems that no matter what game I play, the FPS never stays consistent. Even when I play BF2 on Low settings I only seemto get a constant 35-40 FPS. I have an AMD Athlon XP 2700+ and a gig of PC3200 ram. All my drivers are current, and I scored 5256 in 3dMark05. Was wondering if it could possibly be a PSU problem? My power supply is 425 watts, but my +12v output is only 12a. Was wondering if this could be causing a performance drop?