I'm trying to install one of these cards:
https://www.techpowerup.com/gpu-specs/geforce-6800.c12

But I can't get any driver to work at all, as soon as I finish installing the driver and reboot, I just get no signal. The fan reduces its speed and the PC doesn't appear to have locked up, but can't see anything on screen. I have tried 307.83 (latest), 61.77 (inf modded), 67.66, 71.84 and 93.71, they all do the same thing. I have tried both the DVI and VGA outputs into different displays/adapters, absolutely nothing. Would a corrupt bios still give me a display without drivers installed using the generic VGA display?

Initially I was trying to install it under 98 but was getting the same thing which is why I figured I'd try it for XP since it was period correct but still nothing.