Best External SSD for Mac mini M4 (2026)
A drive that stays on a Mac mini should not borrow the bus power the rear ports are already sharing. Apple’s Mac mini (2024) spec gives the base M4 three Thunderbolt 4 ports on the back, at up to 40 Gb/s, and the M4 Pro three Thunderbolt 5 ports, at up to 120 Gb/s. Both chips have two front USB-C ports at USB 3, up to 10 Gb/s. OWC’s Envoy Ultra manual says that bus-powered drive will not mount as the third bus-powered device on the M4 mini MacMini16,11.
Use the OWC Express 4M2 Ultra. The Express 4M2 Ultra has its own power supply, 19V at 4.74A, 90W. OWC’s table lists up to 6,622 MB/s on Apple silicon with Thunderbolt 5, which is the M4 Pro rear port, and up to 3,200 MB/s on Apple silicon with Thunderbolt 3 or 4, which is the base M4 rear port. Thunderbolt 5 needs macOS 15.3 or later. A single installed drive is listed at up to 1,600 MB/s. The headline figure is a RAID.
Our Top Picks at a Glance
Reviewed October 2026 · Specs checked against the manufacturer pages named below
Own 90W supply. Up to 6,622 MB/s on Thunderbolt 5, 3,200 MB/s on Thunderbolt 4.
Check Price at Amazon Read full review ↓Up to 3,200 MB/s on Apple Silicon and on a Thunderbolt 5 host. Own 12V supply.
Check Price at Amazon Read full review ↓3,189 MB/s on Apple Silicon USB4. One NVMe. Bus-powered.
Check Price at Amazon Read full review ↓Disclosure: This page contains affiliate links. As an Amazon Associate affiliate, we earn a small commission from qualifying purchases at no extra cost to you.
How We Tested
Host ports come from Apple’s Mac mini (2024) tech spec. Enclosure speeds and power supplies come from OWC’s Express 4M2 Ultra page, the USB4 Express 4M2 page, and the Express 1M2 page.
The external SSDs
OWC Express 4M2 Ultra View on Amazon
| Thunderbolt 5 | Up to 6,622 MB/s on Apple silicon with Thunderbolt 5 |
|---|---|
| Thunderbolt 4 | Up to 3,200 MB/s on Apple silicon with Thunderbolt 3 or 4 |
| Power | External supply, 19V at 4.74A, 90W |
| One drive | Single-drive performance up to 1,600 MB/s |
| Software | macOS 15.3 or later for Thunderbolt 5. SoftRAID for the RAID |
OWC’s table for the Express 4M2 Ultra lists up to 6,622 MB/s when the Mac is Apple silicon M3, M4, M5, or newer and the port is Thunderbolt 5. Apple silicon with Thunderbolt 3 or 4 is up to 3,200 MB/s. A PC Thunderbolt 5 host is also 6,622 MB/s. An Intel Mac on Thunderbolt 3 is up to 2,800 MB/s. The supply is 90W, 19V at 4.74A, and the box includes a 0.7 m Thunderbolt 5 cable.
The support manual lists single-drive performance at up to 1,600 MB/s, and it says NVMe sticks with a heatsink are not supported. The volume has to be formatted. SoftRAID is how OWC gets the multi-drive figure, and RAID 4 and RAID 10 are called out as Mac-only at the time of that manual. On the base M4, read the 3,200 MB/s row. On the M4 Pro, read the 6,622 MB/s row, on macOS 15.3 or later.
- Its own power supply, so it is not a bus-powered device
- The 6,622 MB/s row matches an M4 Pro Thunderbolt 5 port
- The 3,200 MB/s row matches a base M4 Thunderbolt 4 port
- A second Thunderbolt 5 port can daisy-chain
- The headline speed wants a RAID, not one stick
- A heatsink on the NVMe is not supported
- Thunderbolt 5 needs macOS 15.3 or later
- The bare enclosure arrives unformatted
OWC USB4 Express 4M2 View on Amazon
| Apple Silicon | Up to 3,200 MB/s on M1 through M4, as USB4 at 40 Gb/s |
|---|---|
| Thunderbolt 5 host | Still runs as USB4 at 40 Gb/s, up to 3,200 MB/s |
| Power | External 12V at 4A |
| Switch | Leave it on USB4 40 Gb/s for macOS 15 |
| One drive | Single-drive performance up to 1,600 MB/s |
OWC lists up to 3,200 MB/s for Apple Silicon M1, M2, M3, and M4 on USB4 at 40 Gb/s, and the same 3,200 MB/s when the host port is Thunderbolt 5, because the enclosure runs as USB4 at 40 Gb/s. The power port is 12V at 4A. The box includes a 0.7 m USB-C cable rated 40 Gb/s. On macOS 15 or later, OWC says to leave the switch on the USB4 40 Gb/s mode.
This is the enclosure to pick when both minis should land on one number. It will not climb to 6,622 MB/s on the M4 Pro. A single drive is up to 1,600 MB/s in the manual. The 10 Gb/s switch position is for hosts that need it, not for these rear ports.
- 3,200 MB/s on both the base M4 and a Thunderbolt 5 host
- Its own 12V supply
- The included cable is a 0.7 m 40 Gb/s USB-C cable
- A mode switch can drop it to 10 Gb/s when a host needs that
- A Thunderbolt 5 port does not raise it to 6,622 MB/s
- One stick tops out at 1,600 MB/s in the manual
- The USB4 switch has to stay on 40 Gb/s for this Mac
- It is an empty enclosure until the NVMe sticks are installed
OWC Express 1M2 View on Amazon
| Apple Silicon | 3,189 MB/s on USB4 at 40 Gb/s |
|---|---|
| Front ports | 990 MB/s on a 10 Gb/s USB-C port |
| Power | Bus-powered |
| Bay | One NVMe |
| Thunderbolt 5 | No Thunderbolt 5 cell on the OWC page |
OWC’s Apple Silicon cell for the Express 1M2 is 3,189 MB/s on USB4 at 40 Gb/s. A 10 Gb/s USB-C host is 990 MB/s, which is the front-port case. The 3,836 MB/s cell is the PC cell. There is no Thunderbolt 5 cell, so an M4 Pro rear port does not inherit the 4M2 Ultra’s 6,622 MB/s.
It is bus-powered and holds one stick. That is the trade for skipping a RAID and a power brick. OWC’s third-device warning names the Envoy Ultra on MacMini16,11. This page does not copy that sentence onto the Express 1M2.
- One drive, without building a four-slot RAID
- The Apple Silicon cell is published
- Ready-to-run versions exist
- The 990 MB/s cell is the honest front-port number
- Bus-powered, unlike the 4M2 enclosures
- No Thunderbolt 5 row
- The 3,836 MB/s cell is for a PC
- An empty unit needs its own NVMe stick
Buying Guide: give the desk drive its own power supply
Comparison Table
| Enclosure | Power | Base M4 rear | M4 Pro rear |
|---|---|---|---|
| 4M2 Ultra | 19V at 4.74A, 90W | Up to 3,200 MB/s | Up to 6,622 MB/s |
| USB4 4M2 | 12V at 4A | Up to 3,200 MB/s | Up to 3,200 MB/s, as USB4 |
| Express 1M2 | Bus power | 3,189 MB/s Apple Silicon cell | No Thunderbolt 5 cell |
Frequently Asked Questions
Does the USB4 Express 4M2 get faster on the M4 Pro?
OWC’s table keeps it at USB4, 40 Gb/s, up to 3,200 MB/s, including on a Thunderbolt 5 port.
Why is one drive slower than the box headline?
The manual lists single-drive performance at up to 1,600 MB/s. The higher figures are for a RAID.
Can the NVMe modules keep their heatsinks?
The Express 4M2 Ultra manual says NVMe SSDs with a heatsink are not supported.
Which macOS does Thunderbolt 5 want?
OWC says Thunderbolt 5 on the 4M2 Ultra requires macOS 15.3 or later.
Final Verdict
The OWC Express 4M2 Ultra is the desk enclosure with its own 90W supply, up to 6,622 MB/s on the M4 Pro and 3,200 MB/s on the base M4. The USB4 Express 4M2 stays at 3,200 MB/s on both chips. The Express 1M2 is the single NVMe, at 3,189 MB/s on the Apple Silicon USB4 cell, and it is bus-powered.