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.

iMac internal storage may be fixed at purchase
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.

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