The OWC Express 1M2 (starts at $119.99; $219.99 for 1TB as tested) has the distinction of being the first external solid-state drive we've tested sporting support for USB4, the latest USB flavor. So it's no surprise that the 1M2 is one of the fastest external SSDs we have encountered, at least when paired with a computer that has either a USB4 or a Thunderbolt 4 port, which both use a USB-C-style connector. The 1M2 will run at reduced speeds if you use it with older hardware, however, and it may require advanced software tweaks to get it working on a PC that does have USB4. Coupled with a relatively high price, this makes it suited only to tinkerers and early adopters who already know they need its groundbreaking speed.

Design: Fins to Beat the Heat

Other World Computing (OWC) is at least as well known for making drive enclosures and housings as it is for making SSDs, and the Express 1M2 is a bit of both. Its silvery frame, designed to hold an M.2 internal SSD, is crafted of aircraft-grade aluminum and is covered with 20 vertical fins. This makes it resemble a large heatsink of the sort you might find cooling components inside a desktop PC, and in fact the fin design does serve to maximize the dissipation of heat from the SSD within. Even so, during testing, the drive frequently felt quite warm to the touch.

The 1M2 is available with a PCI Express 4.0 SSD (the OWC Aura Ultra IV) inside, in capacities ranging from 1TB to 8TB. Alternately, you can buy the enclosure by itself and add your own SSD. In the latter case you also get a tiny screwdriver with which to open the enclosure. OWC notes that the enclosure should work with even larger M.2 SSDs (16TB, say) as they become available.

The 1M2 is large compared with most of today's external SSDs, measuring 0.9 by 2.8 by 5.2 inches (HWD), but it can still fit in a pants or coat pocket. (Just mind that the fin ridges don't get caught on anything.) On one short end of the drive is a USB-C port that supports USB4—the port's label identifies it as "USB4 40Gb/s." The inclusion of a maximum throughput speed is a welcome addition to port (and package) labeling, particularly as some USB4 devices' speeds will max out at only 20Gbps and will be labeled as such.

(Credit: Joseph Maldonado)

The drive's other short end includes a (relatively large) status-light bar, the product name, and the OWC logo.

You can check out the drive family's complete speeds and feeds in the chart below. Note that the sequential read and write scores in the table are raw scores taken directly from OWC's Crystal DiskMark testing at the different capacities, rather than the "polished" scores (rounded to the nearest 100MBps) that most manufacturers provide.

Testing the OWC Express 1M2: Sizzling Speed Over USB4 and Thunderbolt 4

To benchmark the 1M2, we used two different Apple MacBook Pro laptops and our latest Windows storage testbed desktop PC, which we also use to test PCIe 5.0 M.2 SSDs. It consists of an ASRock X670E Taichi motherboard, 32GB of DDR5 memory (two Crucial 16GB DIMMs), two USB4 ports, one PCIe 5.0 x4 M.2 slot (with lanes that have direct access to the CPU), and three PCIe 4.0 slots. It sports an AMD Ryzen 9 7900 CPU using an AMD stock cooler and an Nvidia GeForce RTX 2070 Super card, and it is powered by a Thermaltake Toughpower GF1 Snow 750W PSU. The boot drive is an ADATA Legend 850 PCIe 4.0 SSD. All this is housed in a Praxis Wetbench open-frame case.

After connecting the 1M2 to one of the two native USB4 ports on the testbed's ASRock motherboard, we ran our usual Crystal DiskMark 6.0, PCMark 10 Overall Storage, and 3DMark Storage tests, as well as the AJA System Test. Crystal DiskMark's sequential speed tests provide a traditional measure of drive throughput, simulating best-case, straight-line transfers of large files. The PCMark 10 Storage test measures an SSD's readiness for a wide variety of everyday tasks. The AJA System Test, available for both Windows and Mac, is not normally part of our testing since it's similar to the Blackmagic test we use on macOS (described below), measuring a drive's ability to record and play back video. However, we used it here as a check on the claims that OWC makes in its own benchmarking results.

At first, the 1M2 experienced issues running benchmarks on the Windows testbed. It took several attempts to even run Crystal DiskMark, and when it did complete, the results were inconsistent. Also, both PCMark 10 and 3DMark Storage results were a lot lower than expected (lower than many spinning-disk hard drives). And while AJA read speeds seemed reasonable, write speeds were ridiculously low.

OWC suggested that the problems may be related to a change in a Windows default policy for external storage. Starting in Windows 10 Version 1809, in late 2018, Microsoft changed the default policy for external storage devices from Better Performance to Quick Removal. While the Quick Removal setting allows you to detach an external drive from its port without the risk of losing data, Windows can't cache disk write operations under this setting, which explains the dismally low settings in our initial AJA testing. Changing the setting to Better Performance solved the issue. You can do so either by following the instructions in this Microsoft article or by using OWC's Disk Performance tool; we used the latter. This is a relatively easy problem to fix, but OWC should make it clear that doing so is essential for full performance. If you're not aware, it may take a while for you to realize that you're not getting the speeds for which this SSD is intended.

With that issue out of the way, we ran through all the Windows tests again. In our Crystal DiskMark testing, the 1M2 proved speedy indeed. With sequential read and write throughput speeds hovering around 3,000MBps, it easily outclassed the whole lot of USB 3.2 Gen 2x2 SSDs we compared it with. The only drive in our comparison group in the 1M2's league is the Thunderbolt-only WD Black D50 Game Dock NVMe SSD, which I tested using a Thunderbolt 3-equipped Dell XPS 13 laptop. While the D50's sequential read score effectively matched the 1M2's, its write score lagged by nearly 400MBps. The 1M2's Crystal DiskMark 4K read score is in the middle of our group of comparison drives, and its 4K write score is at the bottom. (The 4K scores aren't as relevant for external drives that don't serve as a PC's main boot disk.)

We are not including a complete table of scores for all the tests we ran on the Windows testbed, because this is the only USB4 drive we have tested and nothing else is directly comparable to it. Still, here are some highlights: It had the highest PCMark 10 score (2,593) of the lot, with only the Seagate FireCuda Gaming SSD coming remotely close, at 2,445. Write and read scores for the video-centric AJA system test were both in the 2,600MBps range.

For macOS testing, we reformatted the 1M2—switching from its native Windows-only NTFS format to the versatile exFAT, which works seamlessly with Windows, macOS, and Linux—on a MacBook Pro with a Thunderbolt 3 connection. We then ran the same tests (Blackmagic, and our own folder transfer test) on a MacBook Pro with an M3 processer over a Thunderbolt 4 connection.

Over a Thunderbolt 3 connection, the 1M2's Blackmagic scores of 948.2MBps for both read and write are what we would expect for a USB 3.2 Gen 2x2 external SSD. With Thunderbolt 4, the results were much faster: 2,625MBps write and 2,180MBps read. It took a mere second to drag, drop, and save our 1.2GB test folder, putting it in an elite group that includes the Samsung Portable SSD T9, the Crucial X10 Pro, the Kingston XS2000, the WD Black D50, and a few other drives.

Verdict: A Zippy External SSD, if You Have What It Takes

Appearing in the form of a brash, finned aluminum heatsink enclosing a PCI Express 4.0 M.2 SSD, the OWC Express 1M2 external SSD cuts a striking figure. It tallied fast benchmark scores over USB4 and Thunderbolt 4, but you'll need a computer with one of these ports to reap its speed benefits. Also, when running the 1M2 on a Windows computer, you may need to tweak an deep setting in the operating system to get consistent performance out of it.

(Credit: Joseph Maldonado)

You pay a premium for the OWC Express 1M2, but if you're looking for speedy transfers of large files, it may fit the bill if you have the right hardware. It comes in capacities up to 8TB, or if you're a DIY-er, you may want to buy the enclosure alone and add your own PCI Express M.2 SSD.

The 1M2 is the first of what we expect to be many USB4 external SSDs. It's off to a good start, though it's not an obvious choice for anyone but early adopters who already know they need its considerable top speeds and have a USB4 or Thunderbolt 4 port to enable them.