Sometimes when I start to use MacBook its cpu speed limit stays at 20% despite the low temperature. I use the app "HOT" to monitor it. Sometimes even when temperature is 60 Celsius cpu speed limit stays at 20%. Only after a reboot it gets to 100%. Or it takes a very very long time.It might be inactivity of half a day or a day. But cannot predict when it will be reset. Is there any reason for this? Or is is it a hardware fault. I have tried clean install of OS. NVRAM SCM ..etc all the resets. But issue stays the same. I have asked the same question here as well. enter image description here

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    The trouble with staring at hundreds of numbers from 'monitoring' apps is that they give you things to worry about, which may be perfectly normal. Do you see any observable performance reduction in your use of the computer? What is this "Speed Limit" parameter actually measuring? Could the problem be a software fault of the monitoring app?
    – benwiggy
    Commented Jun 13, 2021 at 9:30
  • Of course there is a performance issue. System is laggy. Why else I would be bothered with the monitoring apps. :-) . Commented Jun 13, 2021 at 9:53
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    If you have done a clean install of a new OS, along with SMC and NVRAM resets, then I'd say you've ruled out those things as a cause.
    – benwiggy
    Commented Jun 13, 2021 at 10:22
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    Thanks James for the explanation. But I already use intel power gadget , its already in the screen shot. Regarding the issue here it doesn't seem like a temperature issue for reported sensors. Because all the sensors report acceptable values which normally do not lead to throttling. May be there is a temperature issue somewhere else where there are no reported sensors. Commented Jun 13, 2021 at 18:53
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    Does this answer your question? How to find cause of high kernel_task cpu usage?
    – LocalPCGuy
    Commented Apr 26 at 14:31

1 Answer 1


I know this is old but this is most likely answered by this post here, where it recommends to plug in Thunderbolt and other accessories, particularly charging, on the right side ports, not the left hand side. Reasons are outlined in detail in their answer:


I won't quote the whole thing (and may mark this as a duplicate also), but the relevant bits:

Note that high temperature on the right side appears to be ignored by the OS. Plugging everything into the two right ports instead of the left raised the Right temperatures to over 100 degrees, without the fans coming on. No kernel_task either, but the machine becomes unusable from something throttling.

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