Pros & Cons
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- Can easily fit in a pocket
- Fast over a USB4 or Thunderbolt 4 connection
- Excellent PCMark 10 general-storage benchmark results
- Built-in MagSafe connector can secure the SSD to an iPhone
- Can save video as it's being shot
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- No encryption or ruggedization features
Corsair EX400U Specs
| Capacity (Tested) | 2 |
| Controller Maker | Phison |
| Interface (Computer Side) | USB4 |
| Internal Form Factor | Not Applicable |
| Internal or External | External |
| NAND Type | TLC |
| Rated Maximum Sequential Read | 4000 |
| Rated Maximum Sequential Write | 3600 |
| Warranty Length | 3 |
The pocket-size Corsair EX400U (starts at $119.99 for 1TB; $189.99 for the 2TB model we tested) external SSD is a compact, lightweight drive built for high performance, offering both USB4 and Thunderbolt 4 connectivity. With its MagSafe connector, you can attach it to the back of a smartphone, remora-like, for file transfer and even save video to the drive as you're shooting. We're tagging it with an Editors' Choice award as a handy, cost-effective phone companion that can also serve as workaday secondary storage for your PC or Mac.
Design: An SSD Piggybacking on Your Phone
The EX400U has a simple, dense design: a square chassis with rounded corners, finished in matte silver-gray, measuring 0.5 by 2.5 by 2.5 inches (HWD) and weighing just 3.2 ounces. The Corsair logo adorns the top of the drive.
(Credit: Joseph Maldonado)On the bottom, you'll find a striking addition. The drive includes a MagSafe connector—the first I have seen on an SSD—that lets you attach the unit to compatible devices, such as an Apple iPhone 15 or later.
(Credit: Joseph Maldonado)When the drive is connected to the phone via its USB cable, you can transfer content or even record video directly to the drive, freeing your phone's storage space from filling up fast with high-res video. In this respect, it is like the PCMag Editors' Choice Lexar Professional Go Portable SSD With Hub, which is designed to save 4K video in Apple's ProRes format even as the iPhone shoots it. The Go provides a host of other features for iPhone videographers, but with some fundamental drawbacks. For one, it's limited to USB 3.2 Gen 2 speed. Its capacity maxes out at 2TB. And the hub and its bundled extras substantially drive up the cost. With the EX400U, you don't get all the extras. But you do get a faster drive with capacities up to 4TB, and the MagSafe connector for a simplified videography setup—and at a much better cost per gigabyte.
The EX400U's USB Type-C port supports USB4 or Thunderbolt 4. The drive also comes with a 40Gbps USB-C cable that's a foot long. Next to the port is a small status light.
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You can get the EX400U in 1TB, 2TB, and 4TB capacities. It costs more than a typical USB 3.2 Gen 2x2 SSD—it's comparable in price to a base-capacity LaCie Rugged SSD4—but the EX400U ends up being more economical when you look at the 4TB version.
Corsair offers a three-year warranty on the EX400U, a common length for external SSD protection. The drive includes Corsair SSD Toolbox software, offering drive-control options such as secure erase and firmware updates.
Performance Testing: Spot-On USB4 and Thunderbolt 4 Speeds
We put the Corsair EX400U through our suite of benchmark tests for external solid-state drives, including Crystal DiskMark 6.0, the PCMark 10 Overall Storage Test, the 3DMark Storage Test, Blackmagic's Disk Speed Test, and our own custom folder-transfer test. The first three are run on a Windows PC with the drive formatted in NTFS, and the last two on a MacBook Pro using the exFAT format.
In Crystal DiskMark testing, the EX400U's sequential read and write scores were effectively identical to the LaCie Rugged SSD4's, the other USB4 SSD in our comparison group. In the PCMark 10 Storage Data Drive benchmark, which measures a drive's speed at a number of workaday tasks, the EX400U lagged just slightly behind two LaCie SSDs, the Rugged SSD4 and the Rugged SSD Pro5, while besting all the USB 3.2 Gen 2x2 units in our comparison group.
For our Mac-based testing, we used the Thunderbolt 4 MacBook Pro that we typically use for testing external SSDs. The EX400U's Blackmagic speed test results basically matched the LaCie Rugged SSD4's scores with the same Thunderbolt 4 Mac. (Unsurprisingly, the LaCie SSD4's Thunderbolt 5 Blackmagic scores were much faster than its Thunderbolt 4 performance, but they were still well behind the LaCie Pro5's TB5 results.)