iMac 27" 2019 Sonoma - exremely slow

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iMac 27" 2019 Sonoma - exremely slow

So I have an iMac 27" 2019 with a 1TB Fusion Drive running Sonoma and it's dreadfully slow.

I opened it up removed the HD and the ssd on the back of the logic board and fitted a Crucial 2.5" SSD - something I do a lot. Booting into recovery, the install took over 4.5 hours! I then imported a Time Machine backup using migration assistant and this took 8 hours. The machine is still incredibly slow. I then fitted another new SSD - just in case I'd purchased a faulty one and again the machine is incredibly slow, incredibly slow even in Internet recovery and installing a system.

Any ideas?

Posted on Sep 10, 2024 11:07 AM

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Answer 1

Top-ranking reply

den.thed

Level 10

92,530 points

Sep 10, 2024 11:38 AM in response to huwmac

Which of the Crucial 2.5" SATA SSDs did you use...?

(the BX500 or the MX500)

A lot of folks have reported slowness issues using the Crucial BX500 model.

If it is a Crucial BX500, you need to exchange it for a Crucial MX500.

Or return it and get an OWC Mercury Extreme Pro 6G.

If it is an MX500, then another problem could be that you need to enable Trim.

see > https://www.crucial.com/support/articles-faq-ssd/trim-and-ssd-performance-importance?

and > https://kb.plugable.com/data-storage/trim-an-ssd-in-macos

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Answer 2

Allan Jones

Level 9

79,076 points

Sep 10, 2024 4:43 PM in response to huwmac

I opened it up removed the HD and the ssd on the back of the logic board and fitted a Crucial 2.5" SSD

The "drive on the back" runs at up to 2800MB/sec. If you connected the Crucial SATA 2.5" drive to the bus where the Mech drive part of the Fusion system lives, it can at best do 500-600 MB/sec.

Did you enable TRIM on the new drive? Best to do so.

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iMac 27" 2019 Sonoma - exremely slow

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