Shortly after writing the above, I see my core temps have flopped back to the + side of nonsense.

Core Temp 1 (°C)   34.7   31.24   32.71
Core Temp 2 (°C)   326.59   28.09   105.18

It will occasionally flip back to a very large negative temp, but now seems to be stuck on the positive side, so the CTA is not hashing at all since the system thinks it is running too hot and is throttling it off.

What a pain.