I agree with everyone saying clean the fans, it's real easy with a can of compressed air. You mention Youtube specifically. Flash will rape your cpu. I know HTML5 YouTube uses a lot less resources. But you say it happens more often. Make sure the case has 6+ inches of room from the exhaust and intake fans.
On June 25 2010 19:18 Emon_ wrote:
A word of caution - when mounting the heatsink to the motherboard, be careful not to scratch the mobo. If it gets scratched too bad it will also auto-shutdown the computer.
Sounds like you have experience with this
It's ok I have a much more embarassing story. Forgot to put thermal paste on my heatsink. CPU fused to it, while inspecting the problem I decided to reseat all the parts. When I got to taking off the heatsink off, ripped the CPU right out. Pins looked fine but the motherboard... not so much.