I can think of a few possible scenarios.
- Your graphical hardware is overheating.
- There is corrupted remnants of NVIDIA software causing issues.
- Your GPU is loose in the socket, or your motherboard is physically damaged.
Please install a stable latest WHQL release of your driver software after removing them using one of many NVIDIA cleaning tools, and then watch the temperature of your GPU while you are playing a game/etc., that would cause this to occur.
If the temperature seems fine, then you may want to consider booting in to another Windows installation on a separate Hard Drive to check if your current one is corrupted in some way or another.
When all else fails, reseat your GPU in the system and hope for the best. If it's still happening then consider testing your GPU in another PC.