I have been running Crusader Kings II or WoW (never both at the same time) and video screens on an AMD Radeon 6670 HD Diamond edition. It will be fine for between 10 minutes and 3 hours, and then one screen will turn a shade (purple, cyan, green, grey, black), leaving the other fine for a few seconds before it, too, starts flickering, trying to grab everything available, failing and then, around 20 seconds later, shutting the computer off and restarting.
CPU: AMD A6-5400K APU
Driver version: 14.501.1003.0
Monitors: HP S2031 series and Acer S242HL (Note: different native resolutions [HP=1600x900, Acer=1920x1080] and the Windows Screen Resolution identifier thinks there is a third one, but I have it set to disconnected and the driver uninstalled)
Using Chrome browser with HBO Go, Youtube or Blip.tv running, both minimised and not cause this to happen
It does this on both monitors individually as well as with both plugged in, individually it only does the shade