Hello all. I'm trying to benchmark several PCI video cards on an X58 system with a single 33 MHz 3.3V PCI slot (a GA-X58A-UD5), and am having problems getting any of the DirectX 10 cards to work properly:

GeForce 8400 GS - Works but driver crashes during 3DMark Vantage causing a std::exception / Device removed error
GeForce 8500 GT - Computer will not start at all with this card inserted. It just repeatedly power cycles before POST.
GeForce 9500 GT - Works but driver crashes during 3DMark Vantage with same error as the 8400 GS

Vantage was successfully run on the 8400 GS and 8500 GT on other systems, so there cannot be a problem with these cards.

I have duplicates of the 8400 GS and 8500 GT and all four cards malfunction the same way. I have PCIe versions of the same two cards and they work without issue in the same machine. I am using Windows 7 64-bit and the latest compatible Nvidia drivers.

PCI DirectX 9 cards have no problem on this system (though I have not tested these with Vantage.)
PCI DirectX 11 cards have no problem (I have a GeForce GT 610 which completes Vantage without issues). This means there cannot be a problem with the motherboard.

I have completely uninstalled all 3DMark/PCMark products and manually deleted directories and registry keys before reinstalling Vantage but the problem recurs. I have tried two different versions of Vantage with the same result.

Does anyone know what could be going on?

Update: Setting aside for the moment the card that won't POST, I've been trying to get 3DMark Vantage to work on the others. I have tried (1) running the test on Windows 7 32-bit, (2) enabling the Windows desktop basic theme, (3) installing an old Nvidia driver from 2010, and (4) enabling "Flush on low FPS" in the Vantage options. The last one appears to make a difference, as the benchmark now gets further, but it still crashes. I'm also now getting a new error which I hadn't seen before: std::exception / DXGI_ERROR_DEVICE_REMOVED. I have attached screenshots of the two different errors:

Update 2: OK I have finally managed to run 3DMark Vantage on these two cards by setting the TdrLevel registry value to 0 (this is a DWORD on a 64-bit system, not QWORD). Nothing else was required. 'Flush on low FPS' did not need to be enabled. Now I need to figure out why the third card won't POST.