N.H.B. What voltages are you showing on your 3.3v line etc. Have you tried with a motherboard monitoring program running to see if you were getting drops in voltage under load?
P4C800E-Deluxe P4 HT 3.2C@3.84 Zalman 6500-CU WinXP SP-2 DX9.0c
2X512mb HyperX PC4000 @ DDR 480
XFX 6800 Ultra running 455/1300
SB Audigy 2-Klipsch Pro-Medias 4.1
22" Mitsubishi Diamond Pro 2070SB
2-ATA 100 7200 rpm WD Drives