What external storage options are available for the Apple Silicon iMac? Should I buy USB-C or Thunderbolt 3 external storage?

The entry-level Apple Silicon iMac models from both lines -- the iMac "M1" 8 CPU/7 GPU/2 USB-C Shaped Ports 24" (2021) and iMac "M3" 8 CPU/8 GPU/2 Ports 24" (2023) -- have two Thunderbolt / USB 4 ports. The higher-end models from both lines -- the iMac "M1" 8 CPU/8 GPU/4 USB-C Shaped Ports 24" (2021) and iMac "M3" 8 CPU/10 GPU/4 Ports 24" (2023) -- have two Thunderbolt / USB 4 ports and two slower USB 3 ports.

All of these ports use a USB-C shaped connector, so it can be a bit confusing to decide which storage to purchase.

When storage is listed as "USB-C" this generally means it is USB 3 speed with a USB-C shaped connector. Thunderbolt 3 also uses a USB-C shaped connector, but it is significantly faster than USB 3. Accordingly, for either Apple Silicon iMac, you should buy external Thunderbolt 3 storage to maximize its performance.

Simple, High-Performance iMac External Storage

Photo Credit: OWC Envoy Pro FX

Although other drives also will work, a great option is the simple, high-performance plug-and-play OWC Envoy Pro FX from site sponsor Other World Computing.

The OWC Envoy Pro FX is completely SSD-based, provides transfer speeds up to 2800 MB/s, is available in capacities from 240 GB and 2.0 TB, and is dust proof, drop proof, and even water proof up to 30 meters.

High-Capacity, High-Performance iMac External Storage

If you want the option to inexpensively expand your external storage over time, you might prefer the 4-slot M.2 NVMe SSD-based OWC Express 4M2.

Photo Credit: OWC Express 4M2

Compared to the OWC Envoy Pro FX, the OWC Express 4M2 is more complicated, but it also provides up to 2800 MB/s transfer speed and supports as many as four industry-standard internal M.2 NVMe SSDs for as much as 32 TB of storage.

Because the OWC Express 4M2 itself is easy to upgrade, it is straightforward to start with one SSD and add more as needed. Accordingly, this solution can be much neater and easier to manage than having a pile of external drives scattered around your iMac.

To determine whether or not the OWC Express 4M2 could meet your needs, you might find this video that explains how to install storage useful, too:

Whether you prefer simple, plug-and-play storage or an expandable option that maximizes speed and capacity, the OWC Envoy Pro FX and OWC Express 4M2 are ideal options to consider.