Video card problems

On a different PC to the post below, I have had problem since the PSU went
faulty. I changed the PSU, and on a previous post, Kony confirmed that the
voltages on the new one were OK. WinXP refused to boot, though it was stable
elsewhere, and clearing the CMOS did not help. So I formatted the partition
and tried to put on an image I had of XP. This didn't work, the error
appearing again. I reformatted, and installed Win98, which worked OK.
Partition Magic says no partition errors, and scandisk says no errors.
Memtest says no errors.

Everything was corrected detected - all the onboard LAN drivers, video card
drivers, and onboard sound plus motherboard drivers were on the second
partition.

It seems the video card (Asus V8170 DDR64 GeForce 4MX) is partly broken
however. The BIOS is set for 4x AGP. The windows display says that there is
no AGP option. With dxdiag, I only have directdraw test available. There is
no AGP test (greyed out) and the test in between reports a 'generic
failure'. Half Life will work in OpenGL but not D3D, no other 3D game will
work, e.g. Quake 3.
I did try the Nvidia drivers, but it reported no Nvidia hardware. I used
Direct 8.0 and then upgraded to 8.1. I know the card *used* to show 4x AGP
in Windows.

Could the faulty PSU have damaged the video card?
Thanks.
--
Susan