Anticipating a new video card purchase I bought and installed a new psu. It's an ABS Tagan bz series 800W. When I turned on the system all fans and drives rev up, the hdd light turns on for a few seconds then stops, the fans stay on max rpm and nothing happens. So thinking my new psu is faulty I reinstall my old, perfectly working psu, same problem. I have a gateway 503gr, p4 3ghz, with added 2gig gskill mem, ati800xl, and soundblaster audigy2. Please help, thanks.