The Oyen Digital U34 Bolt (starts at $529 for 4TB; $1,099 for 8TB as tested) is the highest-capacity external solid-state drive we've tested that supports the latest USB4 peripheral connection. Although it displayed prodigious speed when we plugged it into a Thunderbolt 4 port—which uses the same USB-C-style oval connector as USB4—our tests didn't produce the high throughput we anticipated when plugged into a USB4 port. Still, even over USB4, the Bolt's data-transfer speeds topped those of typical USB 3.2 Gen 2 external drives, and it set a new high score for an external SSD in the 3DMark Storage gaming benchmark. So it's a tempting option if you require a massive 8TB of storage space on a single external SSD.

Design: A Black Beauty

The matte-black Bolt measures 0.8 by 4.5 by 2.7 inches (HWD) and weighs 8 ounces. Though not as slim and compact as many recent external SSDs, it's still handsome—visibly hefty, but easily able to fit in a pocket. Its four corners are beveled into jewel-like facets (matte black jewels, mind you). Centered at one end are a status light and a USB-C connector replete with a USB4 logo, affirming its maximum throughput of 40Gbps. (Some USB4 products peak at only 20Gbps.)

(Credit: Joseph Maldonado)

Clad in a protective, rubberized sleeve, the U34 Bolt has some ruggedness cred, meeting the US Department of Defense's MIL-STD 810 durability, shock, and impact test standards. However, it does not currently carry an ingress protection (IP) rating for resistance to dust, dirt, and water, as we're used to seeing from rugged drives. Oyen Digital backs the drive with a three-year warranty.

(Credit: Joseph Maldonado)

As mentioned, the U34 Bolt is offered in 4TB and 8TB capacities. Its price tag is admittedly hefty; you can find lower-capacity external SSDs like the 2TB Crucial X9 Pro for around $100. Still, if you need 8TB of storage, it'll cost you, no matter which drive you choose: The U34 Bolt's 8TB version actually costs slightly less than the competing OWC Express 1M2.

Testing the Oyen U34 Bolt: Better Over Thunderbolt

To benchmark the U34 Bolt, we used both an Apple MacBook Pro laptop and our latest Windows storage testbed desktop, which we also use to test PCIe 5.0 M.2 solid-state drives. The latter has 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 with direct access to the CPU), and three PCI Express 4.0 slots. The boot drive is an ADATA Legend 850 PCIe 4.0 SSD. It sports an AMD Ryzen 9 7900 processor with an AMD stock cooler, an Nvidia GeForce RTX 2070 Super graphics card, and a Thermaltake Toughpower GF1 Snow 750-watt PSU.

After connecting the U34 Bolt to one of the desktop's two native USB4 ports, we performed an additional setup step to change our testbed's default policy for external storage. Starting in late 2018 with Windows 10 version 1809, Microsoft changed the operating system's default for external storage devices from Better Performance to Quick Removal. While the latter allows you to unplug an external drive without the risk of losing data, Windows can't cache disk write operations. Changing the setting to Better Performance greatly improves write performance. You can make the change on your PC by following the instructions in this Microsoft article.

We then ran our usual Crystal DiskMark 6.0, PCMark 10 Overall Storage, and 3DMark Storage tests. 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 various everyday tasks.

While the U34 Bolt delivered good PCMark 10 and 3DMark Storage scores on our USB4 testbed (trailing only to the OWC Express 1M2 in the former and setting a new high score in the latter), its Crystal DiskMark results were more in line with a USB 3.2 Gen 2x2 drive—fast for an external SSD, but well below the theoretical potential of USB4 (and the scores of the OWC Express 1M2). We did our share of troubleshooting but could not generate faster speeds over the USB4 connection.

Oyen Digital was disappointed in our results and tried to reproduce our testbed from the system specs we provided. The company generated much better Crystal DiskMark numbers than we did (3,082MBps read; 1,876MBps write). Although we were not able to replicate Oyen's USB4 results, we also reran Crystal DiskMark over a Thunderbolt 4 connection from a Windows 11 machine, the MSI Titan 18 HX, and saw much faster transfers (3,063MBps read; 1,746MBps write).

Verdict: More Than Fast Enough

The Oyen Digital U34 Bolt is a stylish and at least semi-rugged external SSD offered in capacities of 4TB and 8TB. Our test results show that it's lightning-fast over a Thunderbolt 4 connection. And while its USB4 benchmark results in our tests are worse than what Oyen Digital tallied on a replica of our Windows testbed, they're still well ahead of USB 3.2 Gen 2 external drives, including a new record for an external SSD in the 3DMark Storage gaming test.

(Credit: Joseph Maldonado)

We can strongly recommend the U34 Bolt if you plan to use it exclusively or mostly over a Thunderbolt 4 connection. It's less impressive, at least in our experience, over a USB4 connection, which means it may not be a contender if you're willing to spend $1,099 on an external drive specifically because it sports the latest and fastest USB flavor available.