no video output

I have a reference 6RX6800 GPU which was happily running in a water-cooled custom loop for months but suddenly stopped working when trying to turn on the PC. I get VGA error on bios light reporting and the GPU fans are spinning I have reinstalled reference cooler and tried on other motherboards...

Hey guys, I don't know if this is the right forum for this, but today I removed my old display drivers with Display Driver Uninstaller and after rebooting the only thing my monitor shows me is "Input Not Support" Do you know how I could resolve this? I don't know if telling you my specs will...