I have a late 2012 iMac that recently started showing CPU throttling. I don't know what caused it, a couple years ago I upgraded the internal fusion drive and disconnected the internal HDD, removed any excess dust and it worked fine since then. I noticed that throttling starts once the temperature on the platform controller hub die reaches 80 C (which is somewhere in the motherboard, and not the HDD sensor). That's all good and expected, except that the processor remains throttled once the fans kick in and the temperature goes down. Resetting the pram or nvram, or even unplugging it from the A/C doesn't do anything.
- Any suggestions on how to reset or even disable throttling?
- What could have caused this to begin with?