Crucial X8 Portable SSD review: An affordable drive for mainstream users

If you're downloading huge files, look elsewhere.

Credit: Crucial

Crucial’s X8 Portable SSD (1TB as tested) is affordable, fast with everyday tasks, and sports a classy design. It feels nice in the hand and looks good emerging from your pocket. But there is a performance caveat for those who work with very large files and data sets. 

Design and specs

Crucial takes a slightly different approach to the design of its X8 Portable SSD by mixing materials. The main body is anodized aluminum, and there are plastic inserts running across each side, with grippier end caps. They’re all shades of black, and the overall effect is quite nice.

The X8 is one of the larger portable drives I’ve tested. Measuring 4.33 x 0.45 x 2.08 inches (width/depth/height), and weighing just shy of 3.5 ounces, it’s not quite as husky as Samsung’s X5, but more like Sandisk’s Extreme Pro Portable SSD. It sits in your hand nicely. 

The X8 connects using USB 3.2 Gen 2 (10Gbps) and is available in two capacities: 500GB ($119.95 from Crucial) and 1TB ($164.95 on Amazon), the latter being the capacity we tested. The NAND is TLC, which is plenty fast for an external USB SSD—most of the time. Yes, another tease about performance.

crucial x8 ssd flat front Crucial

Crucial’s X8 portable SSD is a handsome drive that’s svelte, but with a nice smooth texture and heft. 

The X8 Portable SSD ships with a Type-C to Type-C cable, with a Type-C to Type-A adapter. 


For the vast majority of our testing, the 1TB Crucial X8 Portable SSD performed like a champ. That covers 99.999% of likely scenarios. However, in the one test where the X8 Portable SSD fell short—the 450GB write test—it fell short by miles. More on that in a bit, and back to the good news in CrystalDiskMark 6 (see darkest bars below).

cdm6 crucial x8 IDG

For 1GB files, the Crucial X8 Portable SSD is as fast as the competition. Longer bars are better.

CrystalDiskMark 6 (shown above) ranked the X8 Portable SSD as basically equal to the competition. The numbers in the chart above are very competitive, and indicate performance for relatively short 1GB read and write tasks. All the other CDM 6 numbers were on track as well.

48gb crucial x8 IDG

When on cache, as it was the vast majority of the time, the X8 is almost as fast as SanDisk’s Extreme Portable Pro. Shorter bars are better.

However, as with the other portable USB SSD drives we’ve tested, real-life performance didn’t match the synthetic benchmark results. The X8 Portable SSD’s 48GB copy test results (shown above) are highly competitive, nearly the equal of those turned in by SanDisk’s top-dog Extreme Portable Pro.

And then...there was the 450GB write test. Most users will never write this large a file, or this amount of data in a single sitting. We do it to test the limits of the drive’s caching techniques. Most external SSDs maintain at anywhere from 400MBps to 600MBps. The Crucial X8 Portable SSD wrote at almost 600MBps for the first 190GB or so, then it sank to a rather sickly 80MBps for the rest of the test. No, the enormously long dark-blue bar you see below is not a good thing. It’s over an hour, where the next-slowest drive took a little under 23 minutes. Yowser.

450gb crucial x8 IDG

The Crucial X8 Portable SSD's long copy rate was good for the first 180GB or so, then it fell off the cliff. Its subsequent pace, barely above 80MBps, was slower than a hard drive. Shorter bars are definitely better. 

We haven’t seen an SSD of any type drop to that low of a write rate in several years, basically since the dawn of TLC. Note, too, that this was the 1TB capacity drive. The 500GB model will likely drop out of cache at the 90GB mark.

The Crucial X8 Portable SSD isn't doing anything weird. Any time an SSD runs out of cache, performance will suffer until the data is moved to the normal NAND, a process that can take several minutes or more. But it's doing it sooner than expected in the write process. Remember, however, that there are few scenarios outside of the video world where you’ll ever write such large files or amounts of data to the drive. 

Testing is performed on Windows 10 64-bit running on a Core i7-5820K/Asus X99 Deluxe system with four 16GB Kingston 2666MHz DDR4 modules, a Zotac (NVidia) GT 710 1GB x2 PCIe graphics card, and an Asmedia ASM2142 USB 3.1 Gen 2 (10Gbs) card. Also on board are a Gigabyte GC-Alpine Thunderbolt 3 card and Softperfect’s Ramdisk 3.4.6, which is used for the 48GB read and write tests.

Smooth and classic

I like the look and feel of the Crucial X8. It’s a great performer the vast majority of the time, and as much as I’m bound to inform you of the slow performance off cache, I can also tell you that I wouldn’t hesitate to use the drive myself.

However, if you use your external SSD to store large video files (raw high-resolution, Ultra Blu-ray rips), better-suited drives include Sandisk’s Extreme Portable Pro and the Samsung T7, which is a fast drive with fingerprint security. 

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Jon L. Jacobi

PC World (US online)
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