your post does not say anyting about your system. in order to determine if 400 watts is enough, we would have to have been told some things like...processor, number of hard drives, video card make/model, sticks of ram and type. any other things you ave plugged in to the beastie.
at first guess i would say that the PSU sounds like the problem. have you tried unp-lugging the fan you installed to see if your FPS returns to what it was before?
You are correct sir i do feel stupid for not suggesting this myself.I guess I'm just used to seeing specs and getting a more detailed description of what is wrong.I also assumed that he had already tried it.TY for the reality check.
AMD X2email@example.com S-939
EVGA NF4 SLI MB
2X EVGA 7800GT IN SLI
2X1GIG DDR IN DC MODE
EXTREME 19IN.MONITOR 1280X1024
THERMALTAKE TOUGHPOWER 850WATT PSU
COOLERMASTER MINI R120