MSI 7600GS AGP Causing crashes

I recently bought an MSI Geforce 7600GS AGP for my system, to replace my Radeon 9700. When installing it, im pretty sure i did everything right... Uninstalled the ATI drivers, rebooted in safemode and used Driver Cleaner to clear out the ATI driver files, restarted, and installed the nvidia drivers. Ive tried using the newest nvidia drivers, and several older version, but nothing seems to work.

Every time I play a game, a minute or so in, my computer crashes. Generally the screen freezes for a few seconds, then goes black for a while, and eventually the computer resets... though one time it gave me a nv4_disp error.

Im pretty stumped here... Anyone have any ideas? At this point the only thing i can think of is that the card might be faulty and need replacing.

At first i thought it might be PSU issue, but i have since bought a nice new Enermax Liberty 400W with +12V1&2@20A, which should be more than enough for a 7600GS AGP.