First things first its not a driver problems - to get into the BIOS you don't need drivers, thats only for windows.
It's gotta be a hardware problem. Check that you've plugged in the PCI-E power plugs into the motherboard.
You could invest in a PSU tester, which you plug the PSU's plugs into and it'll test the outputs.
Also, try and get your hands on an old PCI graphics card, and see if that works