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robertcoogan

macrumors 6502a
Original poster
Apr 5, 2008
844
1,258
Joshua Tree, California
I have a late-2016 MBP (w/ Touch Bar/Retina). Since the last update (to 10.15.5) every time I boot back into macOS from being in Windows 10, kernel_task starts overclocking the CPU. It will run up to near 500%.

Regardless of what time of day it is, if I boot into Windows, then back into macOS, kernel_task will spike usage and keep it there for the remainder of the day. Everything (apps, Internet speed, etc.) becomes sluggish, borderline unusable. It also causes the fans to spin up to 5,800 RPM. In Windows, there are no issues. Graphics and speed are always good - average for Windows 10 under Boot Camp.

But left overnight - in sleep mode with the lid closed - something occurs that resets this mystery kernel_task spike. It has made my MBP somewhat difficult to use since I use applications that are only for Windows, but for only a small part of the day. Now I'm just doing my work on Windows at the end of the day.

I'm not asking for an explanation of kernel_task (I know the issues it can spike). But does anyone know what might be causing the kernel_task process to reset overnight? Being able to maybe run that manually via the Terminal might solve my problems. Restarting & resetting NVRAM hasn't worked.
 
It's definitely not being overclocked, just to be clear. 500% just means that 5 threads are being pushed to 100%.

In any case, are there any other processes other than kernel_task that are showing abnormally high usage when this happens? A lot of the time, kernel_task showing high usage is not directly an issue with kernel_task, but another process constantly sending messages to kernel_task
 
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