Hot hot hot
And as if to protest, the PC went into thermal shutdown. I know how it feels. Tip for Shuttle owners: although the heatpipe doohickey conducts heat away from the CPU very well, it's wasted if you allow the heatsink to get dusty. The main fan blows through the vanes of the heatsink; clogging it up with dust obstructs the airflow and impedes cooling. A quick disassembly and cleaning and all is well.