After upgrading my MacBookPro to macOS Sierra, CPU is running very fast. When I tried to debug the issue, here is what I have found.

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Solutions that I have already tried.

  1. Reset SMC
  2. Reset PRAM
  3. Tried to delete model identifier files (OS is not allowing).
  4. Removed all login items, and all automatically starting apps
  5. Removed all items in /Library/LaunchAgents, /Library/LaunchDaemons, /Library/StartupItems.
  6. Removed all installed software

But still no luck, any leads will be highly appreciated.


  • It is a big issue with Sierra. I downgraded to El-Cap for this single reason and no more issues.
    – Pratik
    Dec 4, 2017 at 3:34
  • @PratikaRana is it with Sierra High as well ?
    – Buntylm
    Dec 4, 2017 at 6:07
  • You can delete model identifier file by disablling SIP (Boot into recovery mode and access terminal via menu bar > utilities then type in this command csrutil disable)
    – Sayan
    Dec 4, 2017 at 13:19
  • Did you say MacBook Pro? MacBook Pros have a maximum CPU percentage of 800% (4 cores x 2 threads x 100%). How is it possible that Kernel task is eating 865%?
    – NoahL
    Dec 4, 2017 at 13:49
  • @Sayan Yes, tried that. no luck. Let me update it
    – Buntylm
    Dec 7, 2017 at 2:25

5 Answers 5


Took apart the case and cleaning out the fans totally solved this for me. There was a lot of lint build-up in both of them so they were not cooling the system adequately.

The reason it causes high CPU load is that Mac creates fake CPU load to slow down the computer as a last-ditch effort to control temperature.

  • 2
    > The reason it causes high CPU load is that Mac creates fake CPU load to slow down the computer as a last-ditch effort to control temperature. That doesn't really make any sense to me. If it's going to thermal throttle, it'll thermal throttle anyways.
    – JMY1000
    Jun 22, 2018 at 2:42
  • 1
    Cleaning the fans meant the laptop could once again cool itself properly so no throttling was necessary. Jun 23, 2018 at 7:00
  • Do you have any source for this? That seems like an unusual thing to do, given the fans would be spinning anyways.
    – JMY1000
    Jun 24, 2018 at 1:25
  • 1
    A source for what exactly? The fans are spinning, but ineffective at cooling because they are full of lint. Therefore the laptop is too hot. Cleaning the fans restores their effectiveness. I'm not sure how this is confusing. Jun 25, 2018 at 3:57
  • 2
    kernel_task is the mechanism by which the CPU is throttled. "If ambient temperature exceeds those limits kernel_task may need to throttle the CPU in an effort to reduce its operating temperature. Occupying a large percentage of the CPU time should be considered normal for the duration of those conditions." discussions.apple.com/thread/8109145 Sep 13, 2018 at 6:27

I had similar issues after switching out the Hdd for an Ssd. The only thing that fixed the issue for me was this link. https://www.davidschlachter.com/misc/kernel_task

If for whatever reason the link doesnt work, this is from the page.

Throttling is implemented as a kernel extension, which Rhys Oxenham suggests disabling by removing the plist in its Resources corresponding to the Mac's model. However, the list of Macs identified by plist files has not been updated for some years. Our 2013 MacBook Air (MacbookAir6,2) is absent. The X86PlatformPlugin.kext (also in the plugins folder of the IOPlatformPluginFamily.kext) has other Macs identified by their motherboard (see comments on this post). In my case, I tried disabling both the ACPI_SMC_PlatformPlugin.kext and X86PlatformPlugin.kext extensions, but this had no effect.

What did end up working for me was to disable the parent kernel extension IOPlatformPluginFamily.kext. So far I've not noted any adverse effects. Obviously I don’t take any responsibility for damages if you try this and have problems.

Here's what I did:

First, I had to disable SIP (since we're running OS X El Capitan) by booting into recovery mode (booting while holding command-R), opening the Terminal (under the Utilities menu), and running the command csrutil disable (more details on StackExchange).

From there, I booted into single user mode by holding Command-S when booting. After mounting the file system (fsck -y; mount -uw /), I made a backup copy of the IOPlatformPluginFamily.kext extension using rsync:

rsync -av /System/Library/Extensions/IOPlatformPluginFamily.kext /Users/Shared/

(To restore the extension from the backup, I would use rsync -av /Users/Shared/IOPlatformPluginFamily.kext /System/Library/Extensions/)

I then deleted the extension and rebooted:

rm -rf /System/Library/Extensions/IOPlatformPluginFamily.kext; shutdown -r now

After booting, the fan still runs at full speed, but the throttling is gone

  • 1
    Please edit the answer to quote the instructions from the link. The link appears to be dead.
    – Nimesh Neema
    Apr 12, 2018 at 16:30
  • Thx for the instructions! I tried removing the IOPlatformPluginFamily.kext, but it was right there after a reboot. But removing only the ACPI_SMC_PlatformPlugin.kext and X86PlatformPlugin.kext worked like a charm for me! Feb 16, 2020 at 22:29

I found this: https://support.apple.com/en-us/HT207359

So the kernel_task daemon “takes” cpu cycles to prevent other tasks to generate heat. This keeps the computer cool.

An update to "Mac Fan Control" had failed, and this was causing the overheating, and thus the kernel_task overload.

After manually downloading the Application and installing - my troubles were over.



Thanks @bmike about the Mac Fan Control app! I was running the latest version but still had this problem every time I'm watching a site like YouTube. The kernel_task process would start hogging up the CPU usage.

Once I turned off the Mac Fan Control app, been using it for the last 2 days and everything has been running smoothly again.


It was a big challenge for me to solve this issue with high speed fan and very much slow system in macbook 2011 pro, After 3 days trying i succeed to solve the issue, by some by deleting file macbookpro8,1 which was my model identifier. Steps In upper os bar click Finder then preference mark Hdd you will see Hdd on your desktop double click on it go to system then library then extensions and IOPlatformPluginFamily.kext now pres ctrl with mouse pad you will show content then contents, plugins, again ctrl with mouseclick show content, content and resources, find your model identfeir and simple delet it again with ctrl and mouse move to recyclebin model identity you can find it in system info more info, restart your pc 100 percent problem solved if your fan is still fast instal app called Macs fan control

Link for video https://youtu.be/ETW-L4fD4AM

  • Please format this so it is readable see help centre apple.stackexchange.com/help/formatting
    – mmmmmm
    Mar 18, 2019 at 9:10
  • 1
    While the video may answer the question it is neither searchable (so the steps you take in the video do not show up if somebody searches on this side) nor does it help the answer to stay on its own (once the video gets deleted the answer looses any value). Can you please edit the question to explain the steps required in enough detail that people can follow them without having to watch the video?
    – nohillside
    Mar 18, 2019 at 11:13

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