Hi BC,
Thanks for checking with your system, I appreciate that. Which CPU and GPU do you have?
For consistency and comparability, I ran Cinebench R23 multi core and got a consistent 99-100C across the 8 p-cores. Temps stayed high for the full 50 seconds or so that it ran, then went back down to the 32-36C range at idle.
To troubleshoot, I reset BIOS and used HP Sure Recover to reset Windows and drivers to factory defaults. This had no effect, so software is ruled out, except possibly the firmware.
Interestingly, the GPU performance has remained as it was when I first started using it 2 months ago. Also, HP hardware diagnostics CPU test gives a pass and I'm not experiencing crashes or hangs.
Looks like I've got a real mystery on my hands here.
(Someone on a different forum suggested the thermal paste could be re-applied to rule out another possible cause but that's really time consuming and I would rather keep it as a last resort.)