iMac 2019 and 2023: Swapping internal SSDs for storage upgrade

On nearly all Apple-Silicon-based Macs – and nearly all Intel-based Macs with T2 security chips – the flash chips providing the storage for the internal SSD are soldered to the motherboard.

Even on those few models where the flash chips are located on their own board, they must be cryptographically "synced" with the T2 chip or Apple Silicon processor chip, the boards are Apple-proprietary … and they are not available as upgrade parts, or are prohibitively expensive.

Old imac is 27" 2019 imac with a 1Tb fusion drive and 8Gb RAM. I love this machine and display. Fusion drive is failing more every day.

Normally I would suggest taking advantage of the

• USB-A (USB 3.0)
• USB-C (USB 3.1 Gen 2, Thunderbolt 3)

ports on the 2019 iMac to add an external SSD. That would avoid the need to pay a repair shop to perform surgery on the 2019 iMac. However, if one or both of the hardware components of the Fusion Drive are failing, it might turn out to be necessary to remove/replace the failing components to keep them from throwing errors that will crash the iMac even when you are starting it up from an external drive.

Then I had this idea! Does it make sense to take the 512 Gb ssd drive from my new imac and put it into the old iMac so that I can get that up and running and upgrade it to Sequoia ... then ... put either a new 1 or 2 Tb ssd into my new iMac?

Not possible. The SSD on the new iMac is not removable.

So, am I crazy? Will a samsung or crucial ssd be fine or should I only use an apple ssd and if so, can anyone buy them or do you have to be an Apple authorised? So much to think about.

If you buy a new internal "circuit board stick" SSD for the 2019 iMac, I would suggest getting it from Other World Computing (Other World Computing – OWC Solid State Drives For iMac 27-Inch (Late 2013 - 2019), and having a repair shop install it. (You may want to check with the repair shop to see if they want to order the SSD directly, if that will make any difference as far as the degree to which they stand behind their work.)

This is because Apple has used various SSDs over the years (especially in notebook computers), and OWC seems to be more on top of stuff than just about any other vendor.

If you buy a slower 3.5" SATA SSD to go in the "hard drive" bay, that could probably be a SSD from just about any vendor. If you are tempted to put in a new "circuit board stick" SSD and a new SATA SSD or HDD, I would advise against combining them into another Fusion Drive. Just keep things simple, with a startup SSD that's big enough that it can act as a startup drive without having to be "Fusioned together" with the other drive.

2nd alternative which is even more expensive, buy a new mac-mini and get my 27" monitor dumbed down to be used as its display. I don't want to have to replace the fusion drive just to use it as a display and I think you don't have to as long as the graphics card is fine, which mine is.

Target Display Mode went away when the first 27" 5K Retina iMac came out in Late 2014. Your iMac does not have it. On top of that, Apple added restrictions so that no current Mac supports using any iMac – even an old one - as a Target Display.

There is a workaround product called Luna Display (by Astropad) that might let you use that 2019 iMac as a second display for a new Mac, but you'll still need a real monitor. Plus, the connection to the 2019 iMac will not be as good as one to a real hardware monitor. The Astropad people themselves say that Luna Display is not recommended for high-motion applications.

That's assuming that your old iMac is in working order. If your iMac is failing due to a bad Fusion Drive, I don't know if that Mac would work reliably even with Luna Display. And it wouldn't be worth sinking a lot of money into that iMac, if the only reason you were making the repairs was to use Luna Display, not to use the iMac for any other purpose.

So if you do get a new Mac mini, you need to plan on getting a real hardware display or display(s) that will do the job even if you can't use the 2019 iMac as an extra screen.

That will not work, because the 2023 24" iMac's storage drive is built into the main board and not removable.

What you need to do connect either the TM or CCC backup drive to the 24" iMac and migrate from it.

see > Transfer to a new Mac with Migration Assistant - Apple Support

Then if the 24" iMac does not have enough storage space for everything...?

You can easily access and/or copy the data that is on the CCC clone to another drive.

Or you can move your Photos, Music or Movie Libraries to another storage drive.

Move your Photos library to save space on your Mac - Apple Support

Change where your music files are stored on Mac - Apple Support

Move Logic Pro for Mac and MainStage content - Apple Support

Move your iMovie for Mac library - Apple Support

Move a Final Cut Pro library - Apple Support

If you want a 27" display, then get an after-market 27" display and connect that to the 24" iMac.

see > Connect an external display to your iMac - Apple Support

Then decide if you want to replace the drive in the 2019 27" iMac or just recycle it.

Approximately no internal components can be swapped between iMac 2019 and iMac 2023. They’re very different. Well, the dust can technically be swapped. But that’s pretty much it.

If you want to keep the old iMac going with a failing Fusion, configure an external SSD and use that.

Or probably much more practically, use the same external SSD connected to the new iMac.

Another possibility: purchase a 27" monitor for use with your 24" M3 iMac.

Your iMac could drive such a monitor at 60 Hz using

A USB-C to USB-C cable rated for 4K video,

A USB-C to DisplayPort adapter, or

A USB-C to HDMI adapter

depending upon what video input(s) the monitor offers.

iMac (24-inch, 2023, Four ports) - Tech Specs - Apple Support

Although monitors with 27" 5K screens (like the one your 2019 iMac has) are expensive, there are plenty of 27" monitors with 4K (3840x2160 pixel) resolution, modern video inputs, IPS panels, and (near-)100% coverage of sRGB. While a 27" 4K monitor wouldn't be quite as sharp as the 27" 5K screen on your 2019 iMac or the 24" 4.5K screen on your 2023 iMac, it might still work for you.

Some monitors have stands that let them pivot to portrait orientation – which can be convenient for text-oriented work (like editing a long word processing document). I don't know if that's important to you; just noting that there are some monitors that have the feature, in case it is.

21jabuka wrote:

Do you have an opinion about turning my old imac into just a display?

iMac retina models aren’t capable of re-use as a display.

Use iMac as a display with target display mode - Apple Support

21jabuka wrote:

Thank you for your reply. Yikes! This confuses me. I've watched a couple of things on youtube that seemed to do just that. Maybe they were older imacs, two of which I still have but that's another story.

Target Display Mode was a feature of many of the iMacs released between 2009 and mid 2014.

24" and 27" iMacs released in 2009 and 2010 could take DisplayPort input. The Technical Specifications for the 27" Late 2009 and 27" Mid 2010 iMacs called this out as a feature. Around the time that Apple released the 27" Late 2009 iMac, a 27" 2560x1440 pixel Dell monitor sold for about $1,200 USD (list) or $1,000 USD (on sale).

Starting in 2011, Macs had Thunderbolt ports. Macs with Thunderbolt ports that supported Target Display Mode did not accept plain DisplayPort input. They required Thunderbolt input, which would have been in short supply back in 2011 when Thunderbolt was still new. If you look at the Technical Specifications of the iMacs which came out between 2011 and mid 2014, I believe you'll find that most of those Technical Specifications make no mention of the Target Display Mode feature at all.

In Late 2014, the first 27" 5K Retina iMac came out, and Target Display Mode went away for good. Later, Apple added restrictions such that no Mac released after 2019, or running anything later than Catalina, supported the use of any iMac as a Target Display.

Use iMac as a display with target display mode - Apple Support

Your 2019 iMac is new enough that you can set it up as an AirPlay Receiver for AirPlay to Mac. That would allow you to use your 2019 iMac as an AirPlay display for another Mac. AirPlay is not as good as a connection to a real hardware monitor, and I believe that even if both of the Macs in question are recent ones, it would not let you use the full 5K resolution of your 27" 5K iMac. Nor could an iMac acting as an AirPlay Receiver be another Mac's only display - you would need at least one real display (such as the built-in screen on the 2023 iMac).

However, since you already have both the 2019 and 2023 iMacs, it would cost you nothing to play with it. If it did not produce satisfactory results, you could simply turn it off.

Continuity features and requirements for Apple devices - Apple Support

Servant of Cats wrote:

…Although monitors with 27" 5K screens (like the one your 2019 iMac has) are expensive, …

Lowest 27” 5K I’ve seen recently was USD$419.99. Samsung Odyssey G8 G80HF 2026.

Seems AI data centers don’t need 5K monitors.

MrHoffman wrote:

Lowest 27” 5K I’ve seen recently was USD$419.99. Samsung Odyssey G8 G80HF 2026.

Samsung's site currently shows a price of $709.99 for that monitor. As does the B&H Photo Video site.

The lowest price I'm seeing in a quick search is $482.50 – and that's for a used one. Also it appears that the monitor has DisplayPort v2.1 and HDMI v2.1 inputs, but no Thunderbolt input. (That suggests that only those Macs which support DisplayPort v2.1 and/or HDMI v2.1 would be able to take advantage of the 5K resolution.)

However, even $709.99 is the lowest price I recall ever seeing for a 27" 5K monitor.