Okay, give this a shot;
Do a full back up and create a restore point.
Download, install, and run Driver Sweeper
to remove the GPU drivers
Download and save to the desktop the newest drivers for your GPU
Power down the PC.
Change video signal cable to onboard video.
boot from the onboard video.
in the device manager, if the GPU is listed uninstall it and disable the onboard video.
turn the computer off.
change the video cable from the onboard to the GPU.
reboot into the bios.
disable the onboard video and set it to detect PCIe first.
save and exit the bios.
when windows finishes booting, disable your antivirus.
install your drivers for the card
reboot the computer.