I had that problem a couple weeks ago when I was back in my hometown. I brought my computer along with me and the airflow in my case was not following the backwards 's' rule. It was also really hot in that room (my core temps were at 48c running at 52c load) and I would get random reboots when I'm gaming or just running a program. Sometimes my monitor would just shut off and I would have to restart. After I got back into Austin, I rearranged my airflow to follow the backwards 's' rule, reapplied thermal compound (artic silver III) to the hsf, and BAM, it was back to normal - 39c running at 43c full load. Everything now is stable and I've gamed, ran powerful applications, and my comp's still running for almost a whole week without restarting. I hope that helped.