iMac super slow, kernel_task hovering at 400 % CPU after upgrade to Sonoma

After I upgraded to Sonoma (no issues prior), my iMac started to run very slow (Retina 5K, 27-inch, 2019, 3 GHz 6-Core Intel Core i5, Sonoma 14.0).

Looking at Activity Monitor, the kernel_task hovers pretty much nonstop at ~400 % CPU.

I cleaned up stuff, went into Recovery and performed a few times the First Aid on all drives. All OK but for this one with the error messages:

"Incomplete or inconsistent CoreStorage physical volume"

"Problems were found with the partition map which might prevent booting" (it does boots, although it takes close to 2 mins).

Any help/suggestion would be greatly appreciated!

Thanks.

iMac 27″

Posted on Oct 13, 2023 11:55 AM

Top-ranking reply

etresoft

Level 9

56,656 points

Posted on Oct 13, 2023 1:34 PM

Your Fusion drive is broken. You can try to reconnect it using instructions here: How to fix a split Fusion Drive - Apple Support

This will erase all of your data. Now's the time to start that Time Machine backup.

However, it should be running better than that, even on just the one drive. I recommend a note to Santa asking for a new iMac.

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18 replies

iatethelotus Author

Level 1

9 points

Oct 17, 2023 7:24 AM in response to etresoft

Guess that's my best next option. Thanks.

iatethelotus Author

Level 1

9 points

Oct 18, 2023 1:09 PM in response to Luis Sequeira1

Thanks again for taking the time to respond.

I'm going to bring it for a clean up/check up, too.

(I removed all outdated apps.)

iatethelotus Author

Level 1

9 points

Oct 18, 2023 1:12 PM in response to Luis Sequeira1

Sorry to bother again, but are there good instructions on the "erase the drive, install a clean system and migrate only the user accounts" process? Never had to do it.

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iMac super slow, kernel_task hovering at 400 % CPU after upgrade to Sonoma