Have you at least tried swapping processors with another motherboard to determine if it's the processor or the motherboard that's broken?
I once changed the heatsink/fan (trying to find one that was quieter) on my 800MHz Duron, and found that the processor temperature would rapidly rise and level off at about 80 degrees C after turning on the power, as compared with other heatsinks that keep the processor at 30-40 degrees. It turns out that the cheap heatsink got sort of bent out of shape when I attached it to the processor, so it just contacted the processor chip along one edge. One bizarre thing about the high temp experience was that the processor ran hotter when sitting at the Windows 98 login window (and would trip the temperature alarm), than when logged in to Windows 98 and doing stuff. Cheers, er, condolences... - Jan
