When you think of external storage, you probably expect it to be significantly slower than the SSD inside your computer. Whether it's a flash drive or even one of the best portable SSDs, the speed compromise is usually pretty noticeable, if not outright unacceptable for certain workloads.

The OWC Express 1M2 is different, though. It leverages USB4 connectivity to provide speeds up to 3,151MB/s. With something that fast, you can kind of stop worrying about not having enough internal storage on your PC. You can use this SSD and it will be basically just as fast, so your workloads can run just as smoothly from it as they would normally.

About this review: OWC sent us the Express 1M2 with a 4TB drive for this review. The company had no input in its content.

Pricing and availability

OWC launched the Express 1M2 on December 7, 2023. It's mostly available through OWC directly, but there are some retail partners, and you can find it on Amazon too.

Pricing starts at $119.99 for the enclosure alone, so you can use your own M.2 SSD. But you can buy the OWC Express 1M2 as an all-in-one solution including an SSD up to 8TB. Prices range from $249.99 to $1,479.99.

Design and build quality

It's built like a tank

If there's one thing I know OWC for, it's that the company focuses heavily on reliability and durability, and that shines through perfectly with the Express 1M2. The chassis is made entirely of metal, and it doesn't feel thin or cheap in any way. It has a reassuring heft, and to go with it, some rubber feet to prevent your table from getting scratched.

The chassis is made entirely of metal

The top of the drive is lined with metal fins that cover almost the entire chassis. This gives the drive a cooler look, but more importantly, it gives it a bigger contact surface for heat dissipation, so the SSD can be kept cool and run at max performance for longer. The chassis can warm up during more intense use, so it's a good thing it's designed to get rid of that excess heat. The front of the drive also has an indicator light that shows when it's being used.

My only complaint in terms of the hardware is that the included USB4 cable is a bit short. It's not a big deal if you're using a laptop or mini PC, but if you have a big desktop tower, your drive may have to dangle a bit depending on where your USB ports are.

Performance

It's so fast

Of course, the reason you buy a USB4 drive to begin with is the speed, and on that front, OWC delivers. The company promises speeds up to 3,151MB/s and in our tests, that holds up. This is because USB4 has a bandwidth of 40Gbps, and all of it can be used for the SSD. OWC actually makes a point of saying even a Thunderbolt drive would be limited to slower speeds, but USB4 doesn't have that problem.

CrystalDiskMark

To test the SSD, I started with CrystalDiskMark, and indeed, you can see just how fast this drive can get. In fact, for some of the tests, speeds actually go much further, reaching nearly 3,700MB/s.

If you compare that to the high-end Samsung T9, for example, that one tops out around 2,000MB/s on paper. But in reality, when connected to a USB4 port, it will most likely be half that speed, as we found in our own testing. The reason for that is that the advertised 2,000MB/s relies on USB 3.2 Gen 2x2, which has 20Gbps of bandwidth. The problem is, almost no PC supports USB 3.2 Gen 2x2, only the standard Gen 2 with 10Gbps speeds. Even if you have a USB4 or Thunderbolt 4 laptop, the USB data link on that port is still just USB 3.2 Gen 2. But because the Express 1M2 is specifically designed for USB4, it can be way faster.

ATTO Disk Benchamrk

I then ran a test in ATTO Disk Benchmark using the default settings. Again, both read and write speeds are incredibly fast once you get to larger I/O sizes. Read speeds can be as high as 3.48GB/s, while writes top out at around 3GB/s.

DiskBench

These synthetic tests are good indicators of speed, but real-life speeds are going to be a bit different. I did try moving files around normally, but to test speeds a bit more scientifically, I used DiskBench. This test basically just moves any file or folder you want between drives, so it tests the effective speed of a file transfer. First, I tried transferring a roughly 27GB folder from my Geekom Mini IT13 to the SSD. This took about 15 seconds, with a transfer rate of 1,804.91MB/s. I then tried transferring a 10GB VHDX file to see how using a single large file might change things. This took just over 5 seconds to transfer, with speeds nearing 1,912.45MB/s.

I also tried transferring the 27GB folder back to my PC, and that took a bit longer, at nearly 19 seconds, which equates to a speed of 1,470.58MB/s. Regardless, transferring files is incredibly fast, and if you have videos stored on your portable drive, you can load them right up in your video editor and it will still work seamlessly.

The enclosure will work with almost any modern device

Of course, it's worth mentioning that the enclosure will work with almost any modern device that has a USB-C port, including Windows PCs, Mac, iPads, and Android, as long as the drive is formatted in a way that every OS can recognize it. I formatted mine for Windows, though.

There are caveats

These performance scores are absolutely fantastic and they should be enough to sell you on this SSD. You have to be aware that if your PC doesn't have a Thunderbolt 4 or USB4 port, it won't support 40Gbps bandwidth. In fact, even if you have Thunderbolt 3, you're out of luck. Those devices will be stuck at a maximum 10Gbps bandwidth, just like standard USB Type-C ports. That's all clear from OWC's marketing, though, so it's fine.

However, I had a bigger problem. When I first tested the SSD, I ran benchmarks across six different PCs and all of them had the same issue where the write SEQ1M Q1T1 speeds in CrystalDiskMark were incredibly low. By that I mean under 20MB/s, often under 10MB/s. Worse, real-life tests like DiskBench also stuck to this speed, so suffice it to say, it was very slow. Read speeds worked fine, but write speeds were nearly unusable.

As it turns out, in order to get the intended performance out of this SSD on a Windows machine, you have to set its operation mode to "Better performance" in Windows. However, Windows defaults external drives to the "Quick removal" operation mode, which makes it easier to unplug devices without risking data corruption or loss. If you plug this drive into a Windows PC without knowing this, you might think it's either broken or just bad.

Fortunately, it's easy to fix, and OWC even has an app to switch the operation modes more easily (though Windows also has this setting built in). However, none of the paperwork inside the box for the SSD made mention of this, so as a customer, I think there's a big risk that the initial experience will be bad. That's something OWC should address, but it's mostly a communication issue. That said, changing the operation mode means you need to be more careful when removing the drive, and you should always eject the drive in Windows before physically unplugging it.

Should you buy the OWC Express 1M2?

If you have a PC or Mac with USB4 or Thunderbolt 4 and you've been wanting fast external storage you can work off of, I'd say you can't go wrong with the OWC Express 1M2. It's incredibly fast, with speeds that nearly match an internal PCIe 3.0 SSD. Sure, there are faster internal SSDs now with PCIe 4.0 or 5.0, but speeds exceeding 3GB/s are still absolutely nothing to scoff at. You can legitimately work off of this external drive and it won't slow you down at all.

It is a somewhat pricy solution compared to typical portable SSDs, but considering that it's upgradeable and faster than just about every alternative, I think that premium is absoluitely justified.

You should buy the OWC Express 1M2 if:

• You work with large sets of data that need to be moved quickly between machines
• You want an external drive you can work directly from without slowing down
• You're looking for an SSD enclosure you can upgrade

You shouldn't buy the OWC Express 1M2 if:

• You don't have a PC with Thunderbolt/USB4 ports and don't plan to buy one
• You don't need the fastest speeds