27-inch iMac flash storage cannot be replaced or upgraded

While a 27-inch iMac with 4TB or 8TB of flash storage has that storage in a slot, the entire line does not support user storage upgrades.

The latest update to the 27-inch iMac included the T2 chip, which handles encryption and security on the computer. Because the SSD is fixed to the logic board for hardware encryption, changing the logic board will erase all data on the drive, and changing the drive is impossible for the same reason.

The document obtained by MacRumors says that the 4TB and 8TB configurations have a flash storage expansion board connected to the logic board via a connector. The expansion board is not present in the 2TB and lower configurations, nor are there third-party modules compatible with it. It also appears that the SATA port internal to the 2018 iMac 5K for Fusion Drives has been omitted in the new model.

The non-upgradeability of the flash storage isn't a big surprise. Apple uses the T2 to secure similar storage on the MacBook Pro, the iMac Pro, and the Mac Pro. Upgrading the Mac Pro requires a firmware update process that has to be executed from a different Mac, which isn't available for any other model, despite using the same storage slots.

The 27-inch iMac is available for purchase (find the best 27-inch iMac prices in our Price Guide) and can be configured with up to 8TB of internal storage, 128GB of RAM, and AMD 5000 series graphics. Customers can also opt for nano-texture glass for an additional $500, similar to the Pro Display XDR.

34 Comments

kent909 730 comments · 15 Years

About 4 years ago

It probably would have been newsworthy if they were upgradable. Why does this surprise you?

Xed 2879 comments · 4 Years

It's too bad, but not expected with the T-series chip. I wish there was a way Apple could resolve this so it could be removable without it being a security issue.

sflocal 6135 comments · 16 Years

The vague issues regarding upgradability of the SSD in the new iMacs is the reason why I ordered it yesterday with the 8TB option. It will be my last Intel-based iMac and I decided to bite my lower lip and max it out so I never have to deal with it ever on that machine.

That being said, with Thunderbolt3, it's really not that much an issue. There are excellent external TB3 enclosures (like from OWC) that will let you install regular NVMe drives to your heart's content. I get that it would be nicer to upgrade the internal drive, but it is what it is.

Mike Wuerthele 6901 comments · 8 Years

kent909 said:

It probably would have been newsworthy if they were upgradable. Why does this surprise you?

Its good that you're familiar with these things historically, but as a reminder, AI is for everybody, and not everybody has the same knowledge that you do.

OutdoorAppDeveloper 1292 comments · 15 Years

For SSD expansion, consider the two thunderbolt/USB 3.1 gen 2 ports. Samsung T7 drives are a great expansion option with around 1GB/s transfer rates and you don't have to open your iMac to upgrade them over time.