Video card troubleshooting

I bought a new Asus 9500 GT video card to replace an aging no-name
6800. I installed it and its drivers, no problems whatsoever.

Then I went to plug something in the USB expansion bay above it, it
popped out of the tool-free case (grr) and shorted out the new card. I
rebooted the system; it no longer detected the video card.

I put the 6800 back in and returned the 9500 to the store. There were
no more 9500's in stock, so I picked up a 9800 GT. I installed it into
the case, and the system booted into Windows.

It runs fine until I start something that requires 3D acceleration
(including Windows Aero), then it immediately locks up the system
hard. Same thing in Linux-- works until I enable wobbly windows or run
glxgears...

Thinking it was a power issue, I hacked together a dedicated power
supply for it. With that, it freezes before booting Windows and shows
the same symptoms as before in Linux.

I tested on another motherboard and it works fine. Have I fried my
PCI-e slot? Does anyone know of any hardware-based method to test it?
Googling tells me there isn't software that can test it, although I've
run a video memory test with the old card and it came up ok. The 6800
still works, and is PCI-e as well.

The possibly borked motherboard is an MSI P43 Neo3-F.

--
Alec
I am pro skub.