thats how my other cpu degraded too, the internal heat is too much so it can't scale anymore.
Is your pot temp still at maximum? because when my cpu degraded my pot was always 10-20C warmer.
Hey man! and welcome.
best way to guess if its a good chip is by seeing what it needs for 5ghz
the guideline is:
5ghz at 1.25v is in some cases 6.8 - 6.9 chip
5ghz at 1.3 - 1.35 is anything from 6.5 to 6.7+