The SSD Review highlighted the Corsair EX400U's exceptional performance, noting it can reach 4GB/s read speeds on Thunderbolt 5 systems, though it cautioned that motherboard implementations often limit USB4 speeds. PCMag's Tony Hoffman praised its unique magnetic Magsafe connector, which allows the drive to securely attach to metal surfaces like the Corsair 6500x case. While the build quality is commended for using Phison controllers and KIOXIA memory, reviewers noted that users must ensure their host device supports USB4 to avoid significant speed bottlenecks. This drive is best suited for users with high-end USB4/Thunderbolt setups who value secure physical attachment, rather than those relying on standard USB 3.2 ports.
Full review
Design and Magnetic Utility
The Corsair EX400U distinguishes itself immediately through its physical form factor, which combines a compact, square chassis with a unique magnetic attachment system. Measuring just 2.56 inches on each side and weighing a mere 1.76 ounces without the cable, it is described by reviewers as the smallest and lightest portable drive they have tested. The construction features an aluminum top plate paired with plastic sides and back, a design choice that Tom's Hardware noted gives the exterior a slightly cheap aesthetic despite the premium internals. However, the functional highlight is the white magnetic ring on the rear, which allows the drive to snap securely onto metal surfaces. This feature is particularly valuable for content creators, as it enables users to attach the drive directly to the back of an iPhone 16 Pro Max via MagSafe, facilitating direct 4K ProRes video capture without the risk of the drive dangling by a fragile cable connection.
The magnetic utility extends beyond Apple devices to any ferrous surface, including Corsair’s own 6500x Dual Chamber PC case, offering a versatile mounting solution for desk setups. The drive includes a short 30cm braided USB-C cable that supports 40Gbps data transfer and 60W power delivery, ensuring that the connection remains tight and secure when magnetically attached. While the build quality is generally praised for its portability, the reliance on a plastic lower shell means the drive lacks the ruggedized, rubberized bumpers found on competitors like the Samsung T9. This makes the EX400U feel more delicate in terms of drop protection, though Corsair does claim it is 1500g shock resistant. The lack of waterproofing is another trade-off for this slim profile, requiring users to handle the device with more care than bulkier, rubberized alternatives.
USB4 Performance and Speed
Performance is the primary selling point of the EX400U, leveraging the Phison PS2251-21 controller and KIOXIA TLC memory to deliver speeds that rival early internal NVMe SSDs. The SSD Review tested the drive on a Thunderbolt 5 system, achieving full rated speeds of 4,000 MB/s read and 3,600 MB/s write for the 2TB and 4TB models, while the 1TB model tested by DigitalCitizen.life hit 3,500 MB/s write speeds. In real-world scenarios, DigitalCitizen.life reported an average transfer speed of 1.81 GB/s when moving a 5.41 GB Windows 11 ISO file, demonstrating consistent high throughput. This performance is nearly double that of standard USB 3.2 Gen 2 drives, making it an exceptional tool for professionals who need to offload large media files quickly. The drive utilizes a pSLC cache of approximately 50 GB to maintain these high speeds during burst transfers, after which performance drops to the native TLC write speeds, a common trait in portable SSDs but one that rarely impacts typical user workflows.
Thermal Management Issues
Despite its impressive speed, the EX400U suffers from significant thermal throttling during sustained workloads, a concern raised by multiple reviewers. Tom's Hardware explicitly listed the metal top getting hot during lengthy sustained writes as a primary con, noting that the aluminum chassis acts as a heat sink but cannot dissipate the heat fast enough to prevent throttling. The SSD Review noted the drive consumes 4.5W during active read and 4W during active write, which is substantial for such a small form factor. This heat generation is not merely a comfort issue; it can lead to reduced performance over time as the drive’s internal temperature rises. Users planning to transfer hundreds of gigabytes of data in a single session should be aware that the drive may slow down significantly after the initial pSLC cache is exhausted and the thermal limits are reached, requiring cooldown periods to maintain peak speeds.
Compatibility and Ecosystem Fit
The EX400U is designed with a strong bias toward the Apple ecosystem and Windows PCs, with official support for macOS 13+, iOS 13+, iPadOS 13+, and Windows 10/11. This makes it an ideal companion for Mac users who can utilize the Corsair SSD Toolbox for health monitoring, firmware updates, and secure wiping. However, compatibility with Android devices is notably poor. DigitalCitizen.life tested the drive with a Samsung Galaxy S23 and a Google Pixel 8, finding that while the Pixel detected the drive, it encountered errors navigating the file system. The reviewer concluded that Android support is effectively non-existent for practical use, recommending alternative drives for Android users. This limitation is critical for potential buyers who rely on their phones for daily storage expansion, as the drive will not function reliably on most Android handsets despite the USB-C connection.
Value and Pricing Analysis
At an MSRP of $139.99 for the 1TB model, the EX400U positions itself as a premium product, though it often appears at lower prices on Amazon and Best Buy. The SSD Tester site listed a price of approximately $265 for the 1TB model at the time of testing, highlighting the volatility in pricing for this category. When compared to the Samsung T9, which offers similar speeds but with a more rugged design, the EX400U’s value proposition hinges on its magnetic utility and compact size. For users who prioritize the ability to magnetically attach their drive to a phone or metal surface, the premium is justified. However, for those who only need raw speed and durability, the plastic construction and thermal issues make it a less compelling value than competitors that offer better build quality at similar price points. The 4TB model, priced at $359.99, offers a lower cost per gigabyte, making it a more attractive option for heavy storage needs.
Who Should Buy This Drive
The Corsair EX400U is best suited for content creators and Apple ecosystem users who need ultra-fast, portable storage that can integrate physically with their devices. The magnetic MagSafe compatibility is a unique feature that solves a specific pain point for videographers shooting 4K ProRes on iPhones, allowing for secure, dangling-free connections. It is also an excellent choice for PC gamers and professionals who need to move large files between a USB4-equipped desktop and a laptop, provided they can manage the thermal throttling during long transfers. Shoppers who value compactness and innovative design over rugged durability will find this drive a strong fit. However, those who require Android compatibility, waterproofing, or sustained high-speed writes without thermal concerns should look elsewhere, as the drive’s strengths are specific to its niche use cases.
Strengths
- +Achieves up to 4GB/s read and 3.6GB/s write speeds on compatible USB4/Thunderbolt 4 systems
- +Features a unique magnetic Magsafe connector for secure attachment to metal surfaces
- +Constructed with high-quality internal components including Phison PS2251-21 controller and KIOXIA TLC memory
- +Compact and lightweight design weighing just over 3oz with shock resistance up to 1500g
Watch-outs
- −Performance drops significantly to 2GB/s on USB 3.2 ports and 1GB/s on lower-speed connections
- −Not waterproof despite being shock resistant
- −Requires specific USB4/Thunderbolt 4 host to achieve advertised maximum speeds
Who this is for
Why you’d buy the Corsair EX400U (1 TB)
- Achieves up to 4GB/s read and 3.6GB/s write speeds on compatible USB4/Thunderbolt 4 systems.
- Features a unique magnetic Magsafe connector for secure attachment to metal surfaces.
- Constructed with high-quality internal components including Phison PS2251-21 controller and KIOXIA TLC memory.
Why you’d skip it
- Performance drops significantly to 2GB/s on USB 3.2 ports and 1GB/s on lower-speed connections.
- Not waterproof despite being shock resistant.
- Requires specific USB4/Thunderbolt 4 host to achieve advertised maximum speeds.
Rating sources
“Overall, it’s a remarkable product that will satisfy its users.”
Our 4.4 score is the average of these published ratings. Ratings marked * were derived from the reviewer’s written analysis or video transcript — the publisher didn’t print an explicit numeric score, so we inferred one from their own words. Click through to verify. More about methodology.
