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Kernal_task % CPU high

  • April 26, 2022
  • 5 replies
  • 22 views
S
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I have a question to ask and i am really hoping some of you experts out there can help me, i recently refurbished a MacBook pro that was not switching on because of water damage. I completed some logic board repair and now have the machine switching back on.

Since this milestone, i have been experiencing an issue, i have no idea of what to do with, i have formatted and erased the SSD that was in the machine and have since installed macOS Monterey 12.3.1. When the machine boots up it is extremely slow and once logged into the macOS and checking activity monitor it is showing that kernal_task % CPU nearing 300%. The machine sometimes runs fine when this % CPU lowers but majority of the time this is not the case and i have no idea why this is happening.

This is a new macOS install so no previous programs installed so i cannot even say this is even anything software related/issues. Nor does running apple diagnostics report anything hardware related, it tells me everything is fine. 

I'd appreciate any suggestions on this at this stage because i just cannot figure this out?

    5 replies

    howie_isaacks
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    • howie_isaacks
    • Esteemed Contributor
    • April 26, 2022

    I just had a MacBook Pro with this same symptom. I never found out for sure if there had been any liquid damage but during troubleshooting, I booted the system into the hardware diagnostic by holding down the D key when I booted up. This was an Intel MacBook Pro. The hardware test showed an issue with the SMC. I had to send it off for repair to get it fixed. It's now working great. Perhaps your MacBook Pro is having the same problem.

    S
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    • simplebeans
    • Author
    • New Contributor
    • April 26, 2022

    I just had a MacBook Pro with this same symptom. I never found out for sure if there had been any liquid damage but during troubleshooting, I booted the system into the hardware diagnostic by holding down the D key when I booted up. This was an Intel MacBook Pro. The hardware test showed an issue with the SMC. I had to send it off for repair to get it fixed. It's now working great. Perhaps your MacBook Pro is having the same problem.


    Hi howie_isaacks i don't know if you read my original post i had already mentioned, I ran apple diagnostics and it did not report anything, it said the machine was fine.

    howie_isaacks
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    • howie_isaacks
    • Esteemed Contributor
    • April 26, 2022

    Hi howie_isaacks i don't know if you read my original post i had already mentioned, I ran apple diagnostics and it did not report anything, it said the machine was fine.


    I guess I missed that part. Sorry. If you have a clean macOS install, it seems logical that there is some hardware issue. I wonder if you would see this activity while booted into macOS recovery. You could launch Terminal while in recovery and type the "top" command to see the most active processes. If you see kernel task running at high CPU there too, then it becomes more likely that this is a hardware problem.

    S
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    • simplebeans
    • Author
    • New Contributor
    • April 26, 2022

    I guess I missed that part. Sorry. If you have a clean macOS install, it seems logical that there is some hardware issue. I wonder if you would see this activity while booted into macOS recovery. You could launch Terminal while in recovery and type the "top" command to see the most active processes. If you see kernel task running at high CPU there too, then it becomes more likely that this is a hardware problem.


    Yes i have just tried that, the machine is still running slow even in macOS recovery then it would normally from past expereince having worked previously on a few of these machines. Even opening terminal takes a bit longer than normal. I just tried to run the command "top" and it informs me '-bash: top: command not found'.

    S
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    • simplebeans
    • Author
    • New Contributor
    • April 29, 2022

    Any other replies on this one? 

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