TL;DR version: I had a similar problem, updating the BIOS fixed it.
Long version:
Bought a new video card, replaced the old card with it, powered on the computer and no video signal was sent to the monitor.
I googled the problem for several days, read many forums, etc, none of the solutions worked.
I suspected that the card is probably dead and was about to give up when I got an idea from somewhere to try updating the BIOS.
As I couldn't even access BIOS with the new card (nothing would appear on the monitor at all), I had to take it out and put my old card in temporarily. I went to the motherboard manufacturer's website (MSI in my case), looked up my model and followed the instructions there.
After updating the BIOS, the new video card worked fine.
I'm guessing the issue was that my motherboard had a PCIe 2.x slot and the card was PCIe 3.x.
Although these PCIe versions are compatible, the old BIOS version probably did not recognize the new standard, while the update added support for it.