More than likely a corrupted/out of date driver. I'd recommend (with the GPU uninstalled), a download of the current drivers (but don't install them yet) and a removal of your currently installed drivers. Shut Down, install the returned GPU making sure the PCI-Ex16 slot is free of dust and debris, and restart. If you're still getting BSODs at this point, I'd say the card was not fixed. If you get to the Windows logon screen, then install the downloaded drivers and restart once more.