Suggestion:  Save the many GF cards with bad VRAM!?

I know of a great many GF cards with artifacts after long service.
If one could disable the bad RAM addresses on these cards, as you do for sys RAM, they could all be put back into service.

As you wrote GpuRamDrive (thx!); I assume you know how to address the VRAM!  :D
I am unaware of a memtest like app for testing and getting the addresses of bad VRAM however?