A66 Silicon Power Armor Review

The Silicon Power Armor A66 (starting at $49.90 for 1TB; $129.99 for the 5TB model we tested) has two big selling points as a portable storage solution. This external hard drive, covered in a rubberized sleeve and a cover for its USB Type-A port, has some outdoor cred, providing protection against bumps, drops, and water. Its 5TB model sells for less than 3 cents per gigabyte, just a bit more than some other hard drives without any rugged features to speak of. The drive comes pre-formatted in NTFS for use with Windows machines, but while it can be reformatted for use with a Mac, not all of our Macs could identify it.

A rugged platter-based portable drive

With all the exposure and hype of high-performance SSDs, you might think HDDs’ days are numbered, but their high capacity and low cost per gigabyte keep them viable, especially in the enterprise market. They still have a following among consumers, despite being considerably slower than the slowest SATA SSDs. (Oddly, Silicon Power lists the A66 as an “external game drive,” but gamers needn’t apply.)

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Taiwan-based Silicon Power provided good value in the internal M.2 SSDs we reviewed (the Silicon Power US70 and UD70). This is the first hard drive we’ve seen from the company, and in general we liked what we saw.

The 5TB Armor A66 seen here measures 0.9 by 3.8 by 5.5 inches (HWD) and weighs 11.6 ounces, like the 4TB model. The 1TB and 2TB versions are thinner (0 .6 x 3.8 x 5.5 inches) and lighter (7.4 ounces) than larger capacity drives, though all are bulkier for portable drives. The photo below shows the 5TB (blue) and 2TB (yellow) units from above, so the difference in thickness is not obvious.

Silicon Power Armor A66 Hard Drives

Silicon Power Armor A66 5TB and 2TB models (Photo: Molly Flores)

As befits a rugged drive, the Armor A66 has a corrugated black plastic top and bottom, with a blue rubber bumper surrounding the sides. The bumper is grooved to hold the included USB-A to USB-A cable. On the right side of the near-short edge is a USB 3.2 Gen 1 Type-A port. The bumper has a rubber seal to cover the port when not in use.

Port Silicon Power Armor A66

USB-A port and cover (Photo: Molly Flores)

Platter HDDs are inherently more fragile than SSDs due to their moving parts, but the Armor A66 is tougher than most. With an internal anti-collision suspension system, it provides military-grade impact protection, meeting MIL-STD 810G Method 516.6 Procedure IV test requirements to survive drops up to 1.22 meters. An IPX4 rating means it’s splash-proof, although it’s not designed to survive submersion and the X in the rating means it’s not rated for dust protection.

A66 Silicone Power Armor

A66 with closed port side (Photo: Molly Flores)

Silicon Power doesn’t provide speed ratings for the Armor A66, but in our tests its sequential read and write speeds were found to be typical of a 5400 rpm SATA III hard drive. It costs a bit more than its unhardened brethren. (At current retail price, the 5TB Armor A66 sells for 2.6 cents per gigabyte, while the 5TB version of WD My Passport, Editors’ Choice winner, costs 2.4 cents per gig.)

The A66 arrives formatted in NTFS for use with Windows computers. Silicon Power notes that you can reformat it for use with Macs. On an Apple Mac Studio running macOS Monterey, I was able to reformat to two Mac compatible formats, ExFat and APFS, but when I connected the drive using either format to one of the USB ports- C/Thunderbolt 3 from our 2016 MacBook Pro (using a Type A to C cable), macOS 10.15 Catalina laptop could not recognize the drive. Thus, we weren’t able to try the Mac-based BlackMagic and Folder Copy tests that we run on most external drives.

Unlike the 5TB WD My Passport and several other portable hard drives, the Armor A66 does not have 256-bit AES hardware encryption.

Armor A66 review: typical (slow) hard drive speed

We were able to run our usual Crystal DiskMark and PCMark 10 global storage tests on our Intel X299-based testbed with the NTFS-formatted A66. Its sequential read and write speeds were found to be typical of a 5,400 RPM platter drive and were within the narrow range of values ​​shown among our comparison drives. The only drive on our chart with the highest scores, the Seagate FireCuda Gaming Hub, is a 7,200 rpm device.

Only two of our comparison hard drives were running our latest PCMark 10 benchmark, which tests a drive’s speed in performing routine tasks such as loading programs and games; the rest of the discs were running a previous version. The A66 had the lowest score of the three.

A hard drive for on-the-go data security

Available in versions up to 5TB, the highest capacity currently available for a portable hard drive, the Silicon Power Armor A66 offers some protection against drops (from desk or pocket height) and rain. You pay a little more for these rugged features than you do for models like the 5TB WD My Passport, our editors’ choice of portable hard drives, and the A66 lacks WD’s hardware encryption (and compatibility Mac turned out to be risky). Still, it’s a good choice as a hard drive you plan to use outdoors or away from your desk.


  • Portable

  • Rated for drop and water protection

  • Available in capacities up to 5TB

  • Modest price for a somewhat robust hard drive

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The inconvenients

  • No hardware encryption

  • Mac compatibility was spotty in our testing

  • Relatively low overall PCMark 10 storage score

The essential

Available in capacities up to 5TB, the current ceiling for a portable hard drive, the Silicon Power Armor A66 combines low-cost storage with some protection from the elements.

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