Sheesh!
Man, that’s a whole lotta hotta.
What’s with the aluminum foil looking appearance on the two chips? Is that Arctic Silver MX-4? Looks more like a metal foil covering. And the blackened areas look like extreme heat transference from an overly hot heatsink positioned just above them. Just how torqued-down (tight) was that heatsink that you removed?
Might also want to check that
all fans are definitely working properly. How “full” is that case with HDs? I’d pull any remaining conventional spinning drives and only use SSDs on the back bus. (Nothing possibly obstructing air flow on the front bus from optimum airflow to the large fan to cool the CPU / heatsink.) AND quite possibly, say a permanent good-bye (remove /replace) any old Apple ADC powered Cinema Displays. Increased demand and thus an interior heat increase overall from a hotter PSU under that ADC load.
Looks as if you’ve already closely approximated the “China Syndrome” …so may be time to lighten the internal load overall and optimize cooling to possibly preserve or extend the life of that Sonnet. AND remove all unnecessary expansion cards, not directly related to your primary tasking. What’s that old
equestrian adage? “Rode hard and put away wet”?
OR:
“Come to kindly terms with your ass, for it bears you.” -John Muir
Very loosely related errata, and just for fun…
https://alumni.berkeley.edu/california-magazine/fall-2017-bugged/zen-and-art-bug-repair(Interesting Steve Jobs passage there too.)
“…so it would never go out of fashion”.