iMac 2019 and 2020 27-inch 5K: Upgrades, Repairs and macOS Support

The 2019 and 2020 27-inch 5K iMacs are the Intel iMacs most worth keeping. They look identical and both carry the model number A2115, but the storage inside is completely different. A 2019 keeps a drive bay and a blade SSD slot, which means an SSD upgrade from $599; a 2020 has its SSD soldered to the logic board and cannot be upgraded internally. Both take more RAM through the rear door, from $329.

All of this is done at our workshop near Castle Hill. Older models are on the iMac repair and upgrades hub.

2019 or 2020: how to tell them apart

• About This Mac, in the Apple menu, reads “iMac (Retina 5K, 27-inch, 2019)” or “iMac (Retina 5K, 27-inch, 2020)”.
• System Information (hold Option and open the Apple menu) shows the Model Identifier under Hardware Overview: iMac19,1 for the 2019, and iMac20,1 or iMac20,2 for the 2020. iMac20,2 is the Radeon Pro 5700 or 5700 XT version.
• The foot of the stand carries A2115 on both, so that number alone will not separate them. The EMC number printed alongside it will: 3194 is a 2019 and 3442 is a 2020.
• The storage. A Fusion Drive or hard drive means a 2019; every 2020 is SSD only.

2019 and 2020 side by side

RAM: up to 128GB through the back

Both models have four SO-DIMM slots behind the rear memory door, and both shipped with 8GB of 2666MHz DDR4. Apple’s memory page gives the 2019 a 64GB maximum (its spec sheet lists the base 3.0GHz model at 32GB), while OWC sells 128GB for it as four 32GB modules. On the 2020, 128GB is Apple’s own official figure.

At the time of writing, a set of four 32GB modules runs to about $1,400 in Sydney before fitting, so it only pays off for large projects or virtual machines that fill the memory. For most people our RAM upgrade from $329 with 16GB fitted is the sensible step, and if you have bought your own modules we fit them from $89.

Storage: where the two models part ways

2019: upgrade it

The 2019 came with a 1TB Fusion Drive as standard, which puts just 32GB of flash in front of a hard drive, or a 2TB Fusion on the top model. It keeps both the 3.5-inch SATA bay and a PCIe blade slot, with no T2 chip in charge of storage, so a full SSD upgrade is possible. An SSD upgrade from us costs from $599 (500GB) or from $699 (1TB), with your data moved across and macOS set up.

A SATA SSD in the drive bay needs the 27-inch thermal sensor issue handled, or the fans run flat out. The other route is an NVMe drive in the blade slot through an adapter, which owners report working in the iMac19,1. Either way the glued display has to come off.

2020: no internal upgrade

On the 2020 the flash chips are soldered to the logic board and run through the T2 security chip. iFixit’s teardown found the old 3.5-inch bay empty with no SATA connector, and rated internal storage serviceability the same as an iPad’s: none. Sources agree on this for the 256GB to 2TB versions. For 4TB and 8TB they disagree about whether part of the storage sits on a separate board, and nobody has confirmed an upgrade.

The practical answer is an external Thunderbolt 3 SSD. It gives you room for photo libraries, projects and backups without opening anything. We can recommend one and set it up; ask when you call.

macOS: Sequoia for the 2019, Tahoe for the 2020

Apple supports the 2019 up to macOS Sequoia 15. Tahoe dropped it, and OpenCore Legacy Patcher has nothing to add, because Sequoia is also the highest macOS the patcher supports. Its developers list restoring audio on the iMac19 family among the unfinished work for Tahoe, and have said they cannot commit to a release. We do not recommend the unofficial forks that claim Tahoe support.

The 2020 runs macOS Tahoe 26, and it is the only Intel iMac that does. At WWDC in June 2025 Apple said “macOS Tahoe will be the final release for Intel Macs”, and that has now happened: macOS 27 arrived on 14 September 2026 and needs Apple silicon.

How long the security updates last

Apple publishes no end dates, but it normally keeps patching the newest macOS plus the previous two; on 14 September 2026 Sequoia and Tahoe received updates and Sonoma did not. On that basis Sequoia is now in its final year, which points to about September 2027 for a 2019, while Tahoe on a 2020 should have roughly two more years. A promise of three years of security updates for Intel Macs after Tahoe is widely reported, but it is not in any Apple document we could find, so do not plan around it.

Apps run on a similar clock. Microsoft 365 and Adobe Creative Cloud both state that they support the three most recent macOS versions, and with macOS 27 out, that leaves Sequoia at the back of the queue. See newer macOS on an older iMac.

The last Intel iMac, and why Windows users keep them

The 2020 27-inch was the last Intel iMac Apple released. For most owners that is a reason to plan the next machine, but for anyone who runs Windows natively it is a reason to hold on. Intel iMacs can start up directly in Windows through Boot Camp; Apple silicon Macs cannot. If your software needs a real Windows install rather than a virtual machine, a well-kept 2020, or a 2019 with an SSD, is one of the last iMacs that will do it.

Faults and repairs on these two models

• A slow 2019. Look at the Fusion Drive first: with only 32GB of flash, most of the work falls on the hard drive. See iMac running slow.
• Fans roaring after an earlier drive swap on a 2019. The first thing to check is whether the thermal sensor was dealt with.
• A 2020 with a storage fault. Because the flash is soldered, this is board-level work, so keep a Time Machine backup. Logic board repair starts from $449, replacement is from $699 and quoted by model, and the $150 bench diagnostic is waived if you go ahead with the repair. See logic board repair.
• No power on either model. A 27-inch power supply replacement is from $479.
• A damaged 5K screen. Glass and panel are one laminated part, from $1,199 fitted on these models. See iMac screen replacement, then read the numbers below.

Keep, upgrade or replace: the numbers

Private sellers on Gumtree were asking a median of about $799 for a working 2019 in September 2026 (seven listings, $400 to $999), and about $999 for a 2020 (nine listings, $700 to $1,750). Refurbished units with a warranty list from about $1,600. The entry-level 24-inch M4 iMac costs $2,399 and an Apple Studio Display alone is $2,599.

• 2019 on its Fusion Drive: upgrade it if you are keeping it. A 1TB SSD and 16GB of RAM together start from $1,028 (SSD from $699, RAM from $329): more than the machine’s median asking price, but under half the price of a new M4, and you keep the 27-inch 5K screen.
• 2020: add RAM and an external SSD, and keep it. There is nothing to replace inside, and Tahoe should get security updates for about two more years.
• Screen on a 2020: borderline. The screen, from $1,199, now costs more than the machine’s private value of about $999, but well under the $1,600 a refurbished one costs or a $2,599 Studio Display. It is worth it only if the rest of the machine is sound and you would rather keep this one than buy a used 2020 privately for less.
• Screen on a 2019: usually not. Fitted from $1,199, it is about one and a half times a working 2019’s median asking price, with about a year of Sequoia security updates left. We would rather copy your data off and help you move on.

Compare the 27-inch 5K iMac 2014–2017 and the 21.5-inch iMac 2015–2019, including the 2019 4K, or read repair or replace an old iMac.

Drop-off and turnaround

Bring your iMac to our workshop near Castle Hill, Monday to Saturday between 8am and 6pm; we do not collect iMacs or work on them onsite. Owners come from the Hills District and across Western Sydney. RAM and SSD jobs usually take one to two business days when parts are in stock, and for screen and board work we give you a timeframe with the quote. Everything carries 12 months’ warranty on parts and labour.

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Questions

Can you upgrade the SSD in a 2020 iMac 27-inch?

Not internally. The 2020's flash chips sit directly on the logic board under the control of the T2 chip, and there is no SATA connector left to use. Sources disagree about the 4TB and 8TB versions, but nobody has confirmed a successful upgrade. The fix is an external Thunderbolt 3 SSD, which we can recommend and set up. The 2019 is different and takes an internal SSD from $599.

Does the 2020 iMac take 128GB of RAM?

Yes. Apple officially supports 128GB in the 2020 27-inch, as four 32GB DDR4 modules in the slots behind the rear door. It shipped with 8GB. Apple lists the 2019 at 64GB, although OWC sells a 128GB kit for it. We fit memory you supply from $89, or our upgrade with 16GB included is from $329.

Can a 2019 iMac run macOS Tahoe?

Not officially, and not through OpenCore Legacy Patcher either. Apple's Tahoe list includes only one Intel iMac, the 2020 27-inch. The patcher tops out at Sequoia and has no Tahoe release, with restoring audio on the 2019 models among the unfinished work. Your 2019 stays on Sequoia, which should keep receiving Apple security updates until about September 2027.

How long will a 2020 iMac get security updates?

Apple has not published a date. Going by its habit of patching the current macOS and the two before it, Tahoe should receive security updates for roughly two years after macOS 27's release in September 2026. Several outlets reported that Apple promised Intel Macs three years of security updates, but we could not find that commitment in any Apple document, so treat it as unconfirmed.

Is the 2020 iMac the last Intel iMac?

Yes. The Retina 5K 27-inch 2020 was the final Intel iMac and the only one supported by macOS Tahoe, the last macOS for Intel Macs. That matters most if you use Boot Camp: Intel iMacs can start up in Windows directly, which Apple silicon Macs cannot. For anyone who needs Windows installed natively, a well-kept 2020 is worth holding on to.

Should I buy a used 2020 iMac or a new M4 iMac?

It depends on what you need. A working 2020 was listed at a median of about $999 on Gumtree in September 2026, against $2,399 for a new 24-inch M4. The 2020 gives you a 27-inch 5K screen, rear-door RAM and Boot Camp, but its macOS upgrades end with Tahoe, while the M4 runs macOS 27. If you buy a 2020, choose the storage size carefully, because it cannot be upgraded later.