How did my post end up ahead of yours?
Well don't leave us hanging, give us the details on the idiocy
It was a power problem. A major power problem.
1. I was using 2 molex power adapters (2 PCIe 6 pins and 4 molex connectors). I only connected three of the connectors...
2. Then I discovered that I had hooked up both my GPUs (the new one and the one with the dead BIOS) to a single line of connectors in my PSU.
I don't know how multi-rail PSUs work, but my PSU has 4x 12v rails, and I suspect it was all loaded up on that poor single rail.
In the end, it turns out that one of my GPUs really did have a dead BIOS so monitor #2 wouldn't have worked no matter what. Whereas
all the energy was going to my dead GPU, so my working GPU didn't have enough juice, which prevented monitor #1 from working as well.