[..]with 3.3V reg and 1.25VCore reg both within 500mV of nominal.
Your definition of "acceptable" is pretty loose to me ! No wonder it caught fire !
Thanks for the picture though, electronics definitely is a fun hobby !!
I remember 15 years ago I was working a crap job testing computer parts returned from the filtered service techs. We would get palettes full every day of various computer parts. I was the one dedicated to testing all the desktop motherboard. 2 or 3 models were famous for, when they came with a "No Power" tag to have 90% of chances to melt/blow a small IC just like you did. When I wanted some fun I used to triage the boards to cherry pick such boards. Would light them up and just stare at the IC smoking, then glowing red then bursting into flames, so cool !!!
Unfortunately for some reason I was the only one finding this funny. Colleagues around me (testing the other types of computer parts), even though 10 or 20 meters behind me, somehow could smell the very first fumes, even before it actually caught fire, and complain violently about it, saying it stunk big time, didn't like the smell of burnt plastic apparently !
So after a bit, I had to limit my fun... I would do it less often.. then when they would complain I would just say "sorry I was not quick enough to unplug it ! " ...