sometimes my pc would go black screen and monitor lost signal, this could happen in windows or while gaming and the game (bf1) would lock up.
upon checking in bios the card would not be detected. sometimes it would show as unknown device in bios.
when booting into windows using onboard graphics it was still not detected in device manager.
if i removed the card and reseated it sometimes it would reappear in bios and windows and work fine until the next black screen. which might occur days later or a few minutes later.
issue was resolved by changing over to spare 8 pin pcie connectors on the power supply.
probably a broken wire on the pcie 8 pin or dodgy psu.
hope this helps others.