I can't think of anything but overheating since you're experiencing this on so many games. But then again, software has been tricky enough in the past to fool the best of them.
Check temps on other components, particularly the motherboard, PCH and even the video card. You can use HWinfo 64 for a comprehensive component performance breakdown.
Have you reset the Windows power plan back to balanced to see what happens? Try that and see if it makes a difference.
I'd like to deploy my troops in her country.