Head-to-head · Best External SSDs

Corsair EX400U (1 TB) vs Crucial X9 Pro

Which is the better buy? Side-by-side on rating, price, strengths, and watch-outs — with the published ratings we averaged to get there.

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The short answer

Corsair EX400U (1 TB) comes out ahead by a clear margin (4.4 vs 4.0). The gap is mostly about fit for purpose — read the strengths below before deciding.

Higher ratedRanked #1 in Best External SSDs

Corsair EX400U (1 TB)

4.4

5 sources1 derived$238.58as of Aug 1

The SSD Review clocked the Corsair EX400U at up to 4GB/s read on Thunderbolt 5 systems while warning that motherboard implementations often limit USB4 speeds. PCMag's Tony Hoffman singled out the unusual magnetic Magsafe connector, which lets the drive attach securely to metal surfaces such as the Corsair 6500x case. Phison controllers and KIOXIA memory earned praise for build quality, though reviewers repeated the caveat: without USB4 support on the host device, expect significant speed bottlenecks. Buy it for a high-end USB4/Thunderbolt setup where secure physical attachment matters, not for a machine with standard USB 3.2 ports.

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

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

$238.58 · Check Price on Amazon Full review →

Ranked #3 in Best External SSDs

Crucial X9 Pro

4.0

7 sources1 derived$89as of May 26

StorageReview and The SSD Review both call out how small the Crucial X9 Pro is: 65x50mm and 1.34 ounces. Single-threaded real-world tests came in slightly under the advertised 1,050MB/s, while multi-threaded workloads tracked the manufacturer's claims closely, which suits creators moving large files fast. Both also credit the rugged build, with IP55 water/dust resistance and drop-proof durability up to 7.5 feet. Peak speeds require a host with USB 3.2 Gen 2; anything less caps performance. It fits professionals who weigh portability and durability above absolute throughput.

Strengths

— Compact dimensions of 65x50mm and lightweight at 1.34 ounces
— High sequential read/write speeds up to 1,050MB/s
— IP55 water and dust resistance rating

Watch-outs

— Single-threaded performance falls slightly below quoted maximums
— Requires USB 3.2 Gen 2 port for optimal speeds

$89 · Check Price on Amazon Full review →

Derived means the reviewer published no score, so one was inferred from their written verdict. Everything else is a number the publisher printed. How we rank.

Specs side-by-side

Spec	Corsair EX400U (1 TB)	Crucial X9 Pro
Interface	USB4 (40Gbps)	USB 3.2 Gen 2
Capacity	1 TB	1TB, 2TB, 4TB
Max Read Speed	3.5 GB/s	Up to 1,050 MB/s
Max Write Speed	3500 MB/s	Up to 1,050 MB/s
Form Factor	Portable	Portable SSD
NAND Type	TLC	TLC

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