I’m struggling with an iMac 2017 21” thats suffering from the high CPU usage. It’s a fresh install and all appears well except this issue has repeated past a clean install (full disk wipe) upgrade and fresh install from USB and then upgrade again to BigSur.
Temps are normal but very high fan usage until I installed Fan Control, there is no excessive temperature on CPU the entire system has been stripped and cleaned by me and rebuilt. The chassis is cool to touch and FC is set to run based on CPU core temps and it’s remaining quiet! There is no malware or other malicious/intensive process running except kernel_task and it’s beyond frustrating.
Apple advise that kernel_task runs when high temps are detedted on CPU (effectively throttling) but others I’ve read disagree with the Apple statement. Based on my experience noted above I also disagree.
I’m wondering if it could be a faulty temp sensor on the CPU (is there is there such a thing?). Like so many I seem to be suffering a problem of unknown origin and am unable to resolve it so far. If anyone else has any useful suggestions I’d be very pleased to hear them.