I had a AMD Sempron just die on me a few months back in my Windows Home Server. It was a single core, but I was able to unlock the second core, and it ran fine as a dual core for over a year. Then I swapped the MB, and the new MB couldn't unlock it, so I ran it as a single core for about a month and then it just died. Everything has been running fine since I just replaced the CPU with a real quad core (PHenom II 840). So it was just the cpu that died, although I did unlock the second core for a while.