SONOMA 14.4 Kernel_Task CPU usage extremely high

I have a 2019 27" iMac with SONOMA 14.4 OSX updated a few days ago.

And I think the issue start to occur after the update.

My Kernel_Task would consume my CPU load up to 60-70%.

Restarting my iMac would flush the memory and everything will be back to normal until I open up any programs like Safari or Adobe Bridge or Photoshop.

The issue would persist even after I closed the program for 30 minutes; Kernel_Task would run high.

If no program is opened, everything would be fine.

I have tried a few trouble shooting method, including creating a new account, did a disk First Aid, the issue would persist.

While the only most affective method is to put my iMac to Sleep mode, it would seem to flush the memory and my CPU load would be back to single digits until I open up another program, the the problem would come back.

I felt this is a bug in SONOMA 14.4 perhaps? Because I think I have experience similar issues before until a new OSX was released.

Does any one have similar issues? or any suggestions?

iMac 21.5″, macOS 10.14

Posted on Mar 24, 2024 5:41 AM

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Posted on Apr 11, 2024 7:32 PM

Issue finally resolved, but here is the brief recaps.

Before I installed SONOMA 14.4 my iMac 2019 was running perfectly fine.

I only have Adobe Photoshop and Lightroom Class running, and occasionally watch Netflix or run some FB games.

Because I do run process a lot of stuff through Adobe from time to time, so I would have my Task Monitor open at all time to monitor my CPU or Memory pressure.

Immediately SONOMA 14.4 was installed, I noticed when I run FB game “Kernel_Task” would run over time, but I do not detect any fan noise.

I Googled up what “Kernal_Task” is, I found out it is a program that controls the cooling fan. So I noticed my iMac would get really hot by touching the back of my unit.

I tried to restart or even shut down to let it cool for a few times, it didn’t work, “Kernal_Task” will stay running extremely high, and my iMac hot.

Until I finally realized if I put it down to “Sleep Mode” it would reset the “Kernel_Task” issue, but it only resets it, not fix it.


I followed the instruction from Apple Online Help from an advisor, I have ran it through Safe Mode, and eventually format the whole thing with a fresh clean MacOS the issue still persist. So finally I contacted Apple Support again, they advise that I need to contact a Senior Advisor, and which lead to an appointment to bring my unit in for a physical check up.


At the check up, they determined the fan is faulty, and it needs to be replaced.

After a week and some money spent, I got my unit back, restarted it via TimeMachine, ran a few test to and so far it looks like it is working fine now. It still runs a bit hot, as I can still feel quite a lot of heat venting from the unit, but at least the Kernel_Task is not running at 70% of my CPU.

I think my situation was, the update somewhat killed my fan, so instead of notifying me what could the the issue, SONOMA is running over time try to initiate the fan.


I am happy I was able to fix it, but I still think that SONOMA 14.4 some what trigged the problem.


The point I wanted to make is, I have very simple and clean Mac setup. I kept plenty of space available on my HDD, I don’t have any VPN, Mac Cleaner program installed, that could cause the problem. I have unplugged all external Hub, printer accessories during my trouble shooting, so it was not caused by fault external devices.


Possible cause of the issue combining my personal experience and what I found online with who has similar issue, and spoke to people with the same issue:

  1. Updating to SONOMA 14.4.1 “could” fix the issue. My friend had the same issue on his MacBook with M1 chip, after updating to 14.4.1 it is fixed.
  2. SONOMA 14.4 is a massive update, so it requires a lot of CPU processing, which probably triggered the overwhelming work on my fan, and eventually killed it. This is my case. So the only solution is to replace the fan.
  3. SONOMA 14.4 has many compatibility issues with either hardware of software, which cause some kind of conflict in programming, and SONOMA is stuck at a loop trying to correct it.
  4. SONOMA 14.4 is not an efficient MacOS, it requires a lot of more CPU usage, or cause more hardware heating, so if you have an older unit, either the fan needs cleaning or the fan is not working efficiently, the program is unable to resolve the issue by software correction, instead it is telling the fan to run faster, harder, but in this vicious cycle, it just cause your computer to run even hotter until something fails. So probably the best solution is to get your unit cleaned up or get a hardware check, because your fan is probably dying or dead.


I still think the culprit is SONOMA 14.4, and maybe as a conspiracy Apple is trying to force you to upgrade to a newer unit, or maybe Apple has just got more MS and releasing more half baked software and have the consumer to test their program for them. I can’t really say, but for the future, I will definitely delay my updates unless it is totally necessary.

In the past, I had faith with Apple, updating whenever I could, and never had an issue, and my iMac could usually last for 5-7 years with no problem.

Surely, with more program update, and especially with AI advancement, my computer is running much slower as it would be in the past, but it would still be useable. I mean, I was still using my 10 year old MacBook Air during my iMac downtime.

Apple do make good products, and I love their eco system, that’s why I have not switched, but I would be cautions with their updates now, since I don’t know wha it’s their business strategy now a days.


And most importantly, do make Backup frequently, TimeMachine is still one of the best backup system I have every seen. My system was 99% functional, with only the exception of Loupedeck require re-installation.

I already was prepared for the worse case scenario I would need to get a new unit, but with my TimeMachine backup, at least I would still have all my work in tack.

42 replies

Apr 8, 2024 12:59 AM in response to KoshAlwaysHere

Best we leave you to figure things out


Really, good luck with this issue and any further issues one may encounter


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Excerpt from above


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Apr 21, 2024 6:28 AM in response to DsTg1015

Here's a giggle. Handbrake 1200% CPU, kernel_task 1.5%

CPU temp 92º (can't tell if it's C or F)

No fan sound, though. And Handbrake never fails to spin fan to max… until now.

CPU temp 89º and falling, still no fan sound. Handbrake only 2% through the task I set it.

No other temps looking *dangerous*, but the air is chill inside, where I live.


Task 2.2% complete, kernel_task 990%, Handbrake 490%ish, CPU temp 75º

Handbrake ETA, about 9 hours now. Didn't look before, and at 2%, I'm not sure it can estimate properly yet. But it has been going for a while.


Let you know if I abandon the test due to fire or something. Temperatures dropping, CPU now 69º and Handbrake getting about 370% CPU…

I think you can see where this is going.


And youtube is already serving me Mark Ellis Reviews - 2017 iMac27 still faster than M3 iMac real-world exporting video from FCP, a task I'd expect to massively advantage Apple Silicon. I'm not tin foil hat enough to believe Cult Of Mac's newsletter leading with '5 Reasons you're mac is slow' is part of an Apple marketing campaign… YET.


Handbrake fighting back, occasionally achieving over 500% CPU, and kernel_task yet to break 990%, temp 67º, at 3.2% completed, and ETA about to pass 16 hours.🙈

How generous the CPU limiting software can be. If only it allowed DaVinci Resolve to play video in sync, so I could do SOMETHING USEFUL. Thanks Apple.

Jun 16, 2024 5:12 PM in response to CABKNY

CABKNY wrote:

If you could provide a link that would be really helpful.

That was maybe 5 years ago?


In any case, it doesn't matter. I don't know what dongle you need for your devices.

Like this looks right, but I'm not sure: https://www.amazon.com/Apple-USB-C-Digital-Multiport-Adapter/dp/B07WF96FY5/ref=asc_df_B07WF96FY5/?tag=hyprod-20&linkCode=df0&hvadid=693535620612&hvpos=&hvnetw=g&hvrand=7242648056512018364&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9032070&hvtargid=pla-814806948641&psc=1&mcid=7284092c01de30f78f025b185e19ab78&gad_source=1

I do buy products from Amazon sometimes. But if I have an option to buy direct, I will do that instead. Big brands like Apple are often counterfeited on the internet. Plus there is always a risk of loss or theft when buying mail order.


This would be a better link: USB-C Digital AV Multiport Adapter - Apple (CA)

Note that this is a Canada link. I don't know what country you live in. The products are the same. Find what you want, print it out, take that printout to the Apple Store.

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SONOMA 14.4 Kernel_Task CPU usage extremely high

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