First restore the original BIOS. See
this thread to learn how to.
If you use Windows 10, import
this registry entry to disable automatic driver update.
Uninstall all display drivers and then perform a cleanup with
Display Driver Uninstaller (DDU) from safe mode.
Take the PC outside, open the case, and remove all the dust with air blower or hair dryer with a cold setting.
Remove the graphics card and blow some air in the x16 PCI express slot.
Carefully remove the heatsink from the graphics card and clean the fans with a toothbrush.
Clean the graphic cards with isopropyl alcohol and cotton swabs. Especially the GPU area and PCIe pins.
When you're done, reapply thermal paste on the GPU, remount the heatsink, plug it back in.
Download and install
this driver from Nvidia's website.
If the graphics card still doesn't work, check if it's under warranty, if it is, just RMA it.
If warranty expired, consider sending it to graphics cards repair lab, if there isn't any in your area, you can try
the oven trick as the last resort.