Thanks! Of course, the computer is of adequate retirement age (it's going to turn 15 in August) or to be relegated to server duty, but it won't hurt to make sure the thermals are all good.
Addendum, that 'similar temperatue on high load' is because it's thermal throttled at that point. See that it went from 2.9GHz to 1.6GHz. It won't ever reach 100 degrees or close to that because of this safety feature.