Example: Samsung X5.įor a more modest cost, there are SSDs which use USB 3.1 Gen 2 (or 3.2 Gen 2x1) and via the USB-C ports on the iMac will deliver ~1000 Mbyte/s. These can have performance similar to the internal SSD (~2000 MByte/s).
To further confuse matters (but out of scope for this question) USB-C ports also support connecting monitors using, for examples, Display Port and HDMI standards.įor maximum speed (and cost) you should be looking for a Thunderbolt 3 SSD storage device. Note that physical USB-C ports which support Thunderbolt 3 have a thunderbolt like symbol next to them. Older Thunderbolt 1 and 2 devices can only be connected using cables which convert to Thunderbolt 3 - the iMac does not directly support Thunderbolt 1 and 2. The current 2021 iMacs support Thunderbolt 3 and USB 4 (using USB-C physical ports).įor the 2020 iMac, Thunderbolt 3 storage devices can only be connected to the USB-C ports and must use Thunderbolt 3 cables. Thunderbolt and USB standards have now converged with Thunderbolt 4 and USB 4 being very similar. The first two iterations of the standard used the Mini DisplayPort physical connector on iMacs, whereas Thunderbolt 3 uses USB-C. Thunderbolt is a different connection standard developed by Intel (in collaboration with Apple) when Apple saw a need for a faster connection than that provided by USB 3. So storage devices specifying USB 3.2 gen2x1 should be compatible with the 10 Gbit/s USB 3.1 gen2 protocol delivered by the USB-C ports.Īs well as the the iMac ports supporting or being compatible with multiple data protocols, most USB storage devices support multiple data protocols and (in many cases) both USB-A and USB-C cables and computer ports.įor an overview of USB standards read Wikipedia. The 5 Gbit/s USB 3.1 gen1 and 3.2 gen1x1 standards are similar to USB 3.0 and storage devices specifying these are generally compatible with USB 3.0 via the USB-A ports.įurther, the 10 Gbit/s USB 3.2 gen2x1 is very close to USB 3.1 gen2. HDD are usually SATA, whilst SSDs might be SATA or NVMe. Common types are are SATA (maximum speed 6 Gbits/s) or NVMe (faster). The drive inside the external device/enclosure.Gen2 (10 Gbits/s), and slower USB 3.1 speeds. USB-C ports: Thunderbolt 3 (maximum speed 40 Gbits/s), USB 3.1.USB-A ports: USB 3.0 (maximum speed 5 Gbits/s) and slower USB 2 and.There is also USB 4, but this is not relevant to 2020 iMac. The data transfer protocol - USB 1, USB 2, USB 3 (and later variants 3.1 and 3.2) and Thunderbolt. The 2020 iMac has four USB Type A (USB-A) and two USB Type C (USB-C) connectors. There are three things which effect compatibility and performance when connecting external storage: