Have you tried going to the bios flash and change the southbridge settings or gfx settings to find the PCI-e?
I haven't! That would be something I would try in the morning. Although I should add that I became desperate and put my old heat damaged i5 in to see if it would work, and it did. So I don't know if the i7 and gpu are just not cooperating. I also have updated my BIOS