The Western Digital Black PCIe SSD (512GB) Review

Final Words

There are still relatively few PCIe SSDs using TLC NAND, and the WD Black is the only one using planar TLC NAND. SanDisk has lately made some of the best planar TLC NAND SSDs with highly effective SLC caching that somewhat insulates them from many of the common performance pitfalls of using TLC NAND. Unfortunately, the competition in the PCIe space is all using either MLC or 3D TLC. Intel's SSD 600p using 3D TLC and Silicon Motion's SM2260 controller is disappointing and performs much worse than the WD Black, but Samsung's 960 EVO doesn't make any mistakes and beats the WD Black across the board (and also beats many of the MLC PCIe SSDs as well).

On some of our more challenging benchmarks, the limitations of planar TLC prove unavoidable in spite of the headroom granted by the PCIe interface, and the WD Black is sometimes outperformed by SATA SSDs including the Samsung 850 EVO and Crucial MX300 that use 3D TLC. Those two SATA drives are always more power efficient than the WD Black whether or not they outperform it.

On the tests where the limited write performance of planar TLC is not a major factor or where the SATA interface can be a serious bottleneck, the WD Black tends to outperform even the best SATA SSDs and often by a wide margin. Even where its throughput is merely on par with good SATA SSDs, the WD Black's latency is much better.

On our ATSB Heavy test, the WD Black showed remarkably little loss of performance when the test was run on a full drive as compared with a freshly-erased drive. This shows that the WD Black's SLC caching strategy is not subject to the horrific failure modes we sometimes see, and that the firmware's flash management strategies are robust instead of being optimized purely for burst performance on short benchmarks in ideal conditions.

Idle power consumption is still a recurring weakness for PCIe SSDs as platform and driver support for PCIe and NVMe power management features is still frequently lacking. There's nothing Western Digital can do about the fact that running a PCIe 3 x4 link at full speed will always require more power than keeping a SATA link running, but they have tackled other aspects of the power management issue with some success. After a few seconds of being idle the WD Black will enter a lower power state even if the operating system's NVMe driver has no support for the advanced power management features of NVMe. This means that in a typical desktop running Windows, the WD Black will have lower idle power than any other NVMe SSD, and it will draw less than a third of what Plextor's SSD based on the same controller uses at idle.

Overall, the WD Black is probably the best PCIe SSD Western Digital could have built using their SanDisk planar TLC NAND. It's clearly a much faster low-end PCIe offering than the Intel SSD 600p despite the latter's potential advantage from using 3D TLC NAND. The pricing will determine which one is a more sensible purchase. The WD Black is not yet shipping in volume, but Western Digital is taking pre-orders with an estimated ship date of March 14. I'm assuming that the current third-party Amazon sellers charging above MSRP will soon be undercut by retailers selling their stock close to MSRP. The price Western Digital is asking is about 10% higher than what the Intel SSD 600p is currently going for. For users with light to moderate workloads the cheaper 600p will still be plenty fast, but if you have a particularly heavy workload or expect to operate the drive nearly full, the WD Black is probably a worthwhile step up. There are also quite a few options just above the WD Black in price that have a clear performance advantage. Among them the Plextor M8Pe seems to have better pricing and performance than the Patriot Hellfire, but there may be other Phison E7 drives besides the Hellfire that are cheap enough to undercut the M8Pe and be a nicee step up from the WD Black.