ADATA XPG SX8000 512GB
A consistently inconsistent SSD
ZEROES AND ONES, that’s all there is to computing, right? Theoretically, yes. In practice, things are a bit more complicated. Enter Adata’s new XPG SX8000 SSD.
Such are the complexities of SSD tech, the SX8000’s headline specifications are little more than a stepping-off point for what the drive actually delivers. It’s still an intriguing SSD on paper, of course.
For starters, it uses Intel’s hot (in more ways than one) new 3D MLC NAND flash memory. Feeding those memory chips is Silicon Motion’s SM2260 controller. It’s a full-featured item with two ARM Cortex cores, eight NAND flash channels, and low-density parity check ( LDPC) error correction. More on that in a moment.
In terms of form factors and interfaces, we’re talking M.2, quad-lane PCIe, and, naturally, the NVMe control protocol. A thoroughly modern SSD. Adata pegs the SX8000’s sequential read performance at up to 2,400MB/s, and its write performance at 1,000MB/s when pseudo-SLC caching is used. As for random performance, the new drives can deliver up to 140,000 4K read/ write IOPS. Those figures are for the 512GB model here and its 1TB sibling. The 128GB and 256GB options are significantly slower.
Back to LDPC. Some would argue that it’s old technology wheeled out to claw back some endurance from the write cycles of Intel’s 3D MLC memory. Meanwhile, the SX8000 is partially dependent on caching technology to achieve its peak speeds—not always great for real-world performance.
With all that in mind, what can we tell you about the SX8000’s performance? It’s complicated. Following our setup routine, which involves brimming the drive with data before wiping it clean, the numbers were hideous. Actually, scratch that. We could see this drive had a few issues even during the setup process. The SX8000 was clearly cycling through performance states, most likely as a consequence of filling, then flushing that pseudo cache.
TESTING TRAGEDY
Diving into the benchmarks, it wasn’t getting anywhere near the claimed numbers, and dropped as far as 600– 700MB/s for sequential reads and writes. Things didn’t look any rosier in our realworld file transfer and compression tests. Over four minutes for our 30GB internal file copy test is nothing short of tragic. Left overnight to idle, however, and the SX8000 performed much, much better.
Peak sequentials of 2,291MB/s and 946MB/s for reads and writes respectively in CrystalMark are pretty much on the money, for instance. It returns some very nice looking numbers in AS SSD’s 4K random access benchmarks, too.
But here’s the catch. Not only is Samsung’s latest solid-state killer, the 960 Pro, capable of much faster performance in most tests, but even after being left to idle, and thus allowing the Adata’s garbage collection routines to do their thing, performance still remains inconsistent.
Very likely, much of this comes down to the properties of NAND flash and its need to be written in blocks, rather than being addressable at bit level. Judging by how hot the drive gets to the touch, it’s possible that thermal throttling is partly to blame, too. Either way, most SSDs now do a good job of compensating for the shortcomings of flash memory. For all the wrong reasons, the SX8000 is a reminder of how far flash memory has come, and how complex it is to implement in a high-performance, small-form-factor SSD. –JEREMY LAIRD