kernel_task issue with imac 27" late 2015

Hello,

I have a iMac 27" late 2015, which within the last couple of months has been running super slowly (intermittently) to the point where the system is unusable and requires a force restart.

Using activity monitor, I've seen when the kernel_task is taking 300% of the CPU and causing everything to come to a halt.

I've read the apple support page regarding kernel_task and understand that its to prevent overheating of the CPU, but it occurs everyday. Facebook webpage could even trigger this. No longer able to play any games, they start off fast but then crawl to a halt.

I've tried the recommendations listed, reset the PRAM AND NVRAM etc.. nothing helps..

The computer is on my desk in my apartment that has AC, so its not in a super hot environment. plenty of space around for air circulation.

Any ideas what can be done to help this?

I realize that this computer is getting somewhat old (the new macos ventura isn't even compatible anymore!), however, Apple no longer makes 27" imacs. The only alternative would be a macstudio + the 27" display, which would run me around $5 (cdn).

iMac

Posted on Oct 30, 2022 10:13 AM

Top-ranking reply

steve626

Level 6

13,791 points

Posted on Oct 30, 2022 5:42 PM

mikeypas wrote:

Cleanmymac serves its purposes. I understand the debate about it, but I install it from time to time to uninstall apps or to check my startup items etc.

whatever your opinion of it, it’s not causing kernel_task to go to 300% because it was doing that even without cleanmymac installed.

same with the SSD, it’s not causing the cpu to go to 80c.

CleanMyMac is bad news, I'd remove it (uninstall completely). The problem is it infiltrates the OS and interferes with normal operations. In some instances, users have found that CleanMyMac "cleaned" out essential files without which the computer stops working normally. CMM is one of the most common reported causes of problems in Apple Discussions.

That said, it is your choice to stay with it.

I am concerned about the SSD. With only ~ 10% free space, it will be working very hard to page to disk and manage virtual memory. One symptom of this could be overheating. Also, Etrecheck reports your disk is performing poorly, possibly failing:

Write speed: 253 MB/s

Read speed: 1683 MB/s

The read speed is ok, but the write speed is very poor, maybe 10-20% of what it should be. I have external bus powered SSDs that are 5 times faster than that. I am suspecting that the internal SSD could be degraded or failing. One way to check this is to download DriveDX and look at the SMART parameters. Run the extended (long) test -- not just the short test. The extended/long test may take 20 minutes or so but may reveal something. The other parts of the report will provide information on how much life is left in the SSD.

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kernel_task issue with imac 27" late 2015

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