Thanks rge. I've run out of thumbs up for all of your testing. It helps everyone understand the gradients that exist and goes further than my testing that was always done at idle without a heatsink installed.

I still read in forums about users running Prime95 with reported core temperatures of ~60C but their heatsinks don't even feel warm. Now we know why. The heat dissipates rapidly from the source when a heatsink is installed.

It confirms TjMax=100C is correct for the E8400 and that the RealTemp calibration method at low MHz / low core voltage, is valid for users that want more accurate core temperatures. It might need to be adjusted by a degree or two based on your recent testing so could you create a small chart showing what temperatures a user should aim for when calibrating? Intel OEM, aftermarket air and water. I might have some fun with my drill this week to see what I can learn.