Knowing nothing about how survival/durability testing is done in VLSI: how did you do the empirical tests?

For example, I know that thermal samples for the Pentium 5-era Xeon (Jayhawk) were produced, but I'd always wondered Intel went from the dummy to realizing "oh, shit, this is going to be way too hot in the long run."

I can’t really speak to the thermals other than as an input to my work. I was narrowly focused on the cyclic loading based on the temperature gradients (etc.) I was given.