Sorry if this is somewhat offtopic, but the 3 posts above mine (especially GeneralQuery's mentioning NVIDIA), reminds me of the time when I was porting some code from Direct3D8 to Direct3D9 from an older version of the NVSDK (5.21). I was particularly interested in the bump refraction demo submitted from Japan using a proprietary texture format "NVHS". I never found anywhere in NVIDIA's documentation that this texture format was only supported on the GeForce 3 and 4 Ti series GPUs, so I was getting upset that I couldn't get the feature to work on my 8400 GS M. I assumed it was just a problem with my drivers, but to be sure I asked some other people to verify that it does or doesn't work on their machines. Turns out that when checking the device caps, the driver claims the texture format was supported on all NVIDIA cards, but creating the texture using that format would always fail unless your GPU was from the NV2x series.

I tried to warn NVIDIA of this driver bug, but to no avail. It's not too relavent now since no one used that format (Q8W8V8U8 was more compatible anyway), and DirectX9 is dying slowly but surely either way.