Originally Posted by
Nanilith
Try the following:
0) Set all your WoW in-game settings to minimum, unload all add-ons.
1) Uninstall then install your graphics card drivers, then your motherboard drivers if that doesn't work.
2) System Restore Windows to a point in time before the issue began.
3) Ensure that Windows is up-to-date.
4) Uninstall then install World of Warcraft.
5) Reinstall Windows.
If these don't work, it's probably a hardware issue like your PSU dying. Is your power supply fan making alot of noise? It could be on its way out.