iMac with HD performs considerably slow

Georgia_L15 wrote:

Only if I new the mistake I was making.....

I bought a refurbed 2019 iMac from Apple in December for £1000. I only decided to buy this one instead of a brand new because I got impatient and there were no new iMacs available till mid-January.

But I thought it is from Apple, it should be fine.

So the machine from day one is not performing as expected. It was on Catalina. Upgraded to Big Sur, nothing changed. Contacted support a couple of times. We erased everything and re-intalled. This has might slightly fixed the problem but not completely.

I was then told to send it to an authorised service point to check it. So I did. The technician told me the performance issue was not due to a hardware fault and is due to a limitation issue with APFS volume format on hard drives.

While APFS is fully compatible on hard drives (from macOS Mojave to macOS Big Sur) it does cause the drive to run slower as the format was originally intended for Mac's with an internal Solid State Drive (and was made compatible later on).

Yea' the entry level 21.5" iMac only has a 5400rpm HDD.

My iMac's internal drive is a hard drive which is why the machine may run considerably slow compared to older models of iMacs that were installed with either macOS High Sierra (last release of macOS to use the older Mac drive format on their internal hard drive) or an older Mac operating system.

The previously used Mac format for internal drives (and still uses on Time Machine external hard drives) would be Mac OS Extended (Journaled).

Reverting to macOS High Sierra would not be a potential fix option for my iMac as my model originally shipped with macOS Mojave (your iMac would not support or allow us to reinstall macOS High Sierra).

You can not natively install or run an older macOS than originally came on that machine.

If I'll decide to replace the HD with a SSD I am losing my warranty. Also, as non-Apple 2.5" SATA SSDs have different sensors to the original hard drive, the iMac's Fan might not run normally and at full speed during use constantly (this can vary from drive to drive).

Also, while this is not affecting the machine's performance, I consider it as unacceptable when you pay £1000 and buy something straight from Apple and the screen is slightly misaligned.

So, any suggestions on SSDs you have used on an iMac and they work well?

iMac's are sealed units and very difficult to work on and upgrade. Instead of risking damage and voiding your warranty, it would be better to install macOS on an external USB-C SSD, then use that as your startup disk.

https://eshop.macsales.com/shop/owc-envoy-pro-ex-thunderbolt-3?ds_rl=1242044&gclid=EAIaIQobChMI7-Wd3cTQ7gIVNAytBh0TeAR8EAAYASAAEgJNM_D_BwE&gclsrc=aw.ds

https://eshop.macsales.com/item/OWC/TB3ENVP10/

https://www.crucial.com/ssd/x8/CT1000X8SSD9

If it is a 21.5" then the internal HD is the bottleneck, it's only 5400 RPM and there is nothing you can do to speed up the HD. What I'd recommend is one of https://eshop.macsales.com/item/OWC/TB3ENVP10/ and then install Mac OS onto the SSD and migrate your Time Machine backup to the new SSD. This will dramatically improve performance. Macsales is a US company however so shipping from the USA would be expensive, what I'd recommend is using this link OWC European Reseller to find a reseller in the UK where you appear to be located. Simply click the map and contact them.

Another option (but slower than a Thunderbolt 3 device) is:

https://eshop.macsales.com/item/OWC/MS8U3SSDT1.0/ and a https://eshop.macsales.com/item/OWC/MOTGPWR/