I had my computer do this awhile ago, but I had fixed it. My GPU fan wasn't spinning, causing it to overheat and then auto restart to prevent damage. This is no longer the issue as my graphics card fan is fully functional and my temperatures are now what seem to be normal. This isn't a gaming GPU, but I'm not really playing any stressful games. I have a AMD Radeon HD 6670 1GB, and I'm playing Minecraft. I downloaded a program to monitor temperatures and my graphics card never rises above 121* F while playing Minecraft. After awhile of playing Minecraft or any other mildly stressful application, my computer auto restarts. I know it is not my CPU, which never rises above 65* F. I cannot imagine what could be overheating, or if that is even the problem. No recent hardware changes, nor software changes. Please help; any and all is appreciated.