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Kernel task cpu usage too high

Hi guys, after upgrading this afternoon to monterey OS, the cpu % of kernel task is too high at >250% even if no app is opened. Can someone help me how to deal with this?

I am using iMac2017

iMac 27″ 5K, macOS 12.0

Posted on Nov 24, 2021 7:46 AM

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Question marked as Top-ranking reply

Posted on Nov 24, 2021 7:55 AM

How long after upgrading to Monterey?

After upgrading there are tasks running like reindexing the drives, working on phot library and some other things.


If it has been a while try booting to Safe mode and then a normal start. Booting to Safe Mode takes minutes.

How to use safe mode on your Mac - Apple Support

10 replies

Dec 3, 2021 9:19 AM in response to eldie762

I have been experiencing this exact same issue since upgrading to Monterey 12.0.1. I believe I've discovered what triggers it - at least on the MacBook Pro hardware (mine is Intel CPU).


My suspicion is that the issue is related to power management in some way. I don't know enough about reading or understanding a spindump file to confirm.


Here is what I have tested and confirmed did NOT work for me:


  1. I thought the issue was related to Spotlight index so I disabled several index categories in Spotlight settings. Ultimately I also disabled Spotlight, completely deleted my index, re-enabled Spotlight, and rebuilt the entire index. This did not solve the issue.
  2. I tried booting in Safe Mode. This did not solve the issue.
  3. I reset NVRAM and SMC. Neither solved the issue.
  4. I booted in Recovery Mode and ran first aid on all volumes. This did not solve the issue.
  5. I modified/disabled several system preferences settings mentioned in other threads including: graphics switching, optimized battery charging, and reduce transparency. None of those solved the issue.


Ultimately I discovered the following:


  1. When the battery is low and I plug the computer into charge, kernel_task ends up consuming almost the entire CPU capacity within 60 seconds. It will quickly rise to 450% and stay anywhere between that number and upwards of 600%.
  2. It does this regardless of whether applications are open or not.
  3. If I unplug the power cable, the kernel_task process returns to the 3% - 6% range.
  4. If I re-plug the power cable, the kernel_task process jumps back up to the 450% - 600% range.
  5. Once the battery reaches a charge of 70%, the kernel_task process returns to the 3% - 6% range.
  6. It doesn't matter what power charger I use. Tested with 2 variations I have:
    • Apple (OEM) 87W USB-C Power Adapter
    • Anker Power Port III 65W USB-C Power Adapter


Sorry that this does not immediately suggest a good reason as to why you are experiencing the same issue since you're on an iMac which never transitions between AC and battery. But thought I would share what I have found incase it helps put others on the right path. Perhaps there is a shared power management issue I'm just not familiar with. This has been super frustrating given the fact that it essentially bricks all other usage of the computer because kernel_task is consuming all available resources. Interested to hear if anyone else suffering this issue can duplicate and confirm what I have seen.


Details of my hardware and software are:


macOS Monterey 12.0.1

MacBookPro14,3 (15-inch, 2017, touch bar)

2.9 GHz Quad-Core Intel i7

16GB RAM

Radeon Pro 560 4 GB / Intel HD 630 1536 MB

Dec 13, 2021 5:10 AM in response to dusthaines

Thanks for the reply guys.


I just want to give you guys an update what has happened to my imac :


4 Dec : Brought imac in apple service center and found out the fan was spinning very slow. They recommended to replace the fan. 


10 Dec : They called me and said that after replacing the fan kernel task usage is still high. They recommended to replace the logic board and retain the old fan. 


morning of 11 Dec : They called me again and said after replacing the logic board the problem still exist. They recommended to replace the fan as well so now - new logic board and new fan. 


Afternoon of 11 Dec : They called and said after having the new logic board and new fan, issue is still there. They told me that their ENGINEER will look into this matter and give top priority - to call me in a couple of days


13 Dec : They called me and said they will need a couple more days to determine the problem and said that the speaker will be replaced as well. 


To be continued ....

Dec 20, 2021 8:33 AM in response to ternelkask

So here is the final update on my iMac:


17th Dec : Collected my iMac in Apple Service Center, kernel issue has been resolved and paid USD611 for the login board + fan + service. But as you can see on my 11th of Dec afternoon update they were saying a new logic board and a new fan did not solve the issue so I would think both my logic board and fan are in good condition right? Also according to them I was not charged on the power supply which they also replaced. Could it be the real culprit after Monterey upgrade the power supply malfunctioned? I don’t know, only apple would 🤔🤔🤔

Kernel task cpu usage too high

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