The Western Digital WD Black SN750 SSD Review: Why Fix What Isn't Broken?

Whole-Drive Fill

This test starts with a freshly-erased drive and fills it with 128kB sequential writes at queue depth 32, recording the write speed for each 1GB segment. This test is not representative of any ordinary client/consumer usage pattern, but it does allow us to observe transitions in the drive's behavior as it fills up. This can allow us to estimate the size of any SLC write cache, and get a sense for how much performance remains on the rare occasions where real-world usage keeps writing data after filling the cache.

WD Black SN750 1TB (3rd Gen) WD Black 1TB (2nd Gen) Samsung 970 EVO 1TB HP EX920 1TB Plextor M9PeGN 1TB Corsair Force Series MP510 960GB Silicon Motion SM2262EN 2TB Toshiba XG6 1TB Intel Optane SSD 900P 280GB WD Blue 1TB 3D NAND WD Black 7200RPM 1TB

The WD Black SN750's behavior during a full drive write is quite similar to that of its predecessor, albeit with a 5% improvement in write speed after the SLC cache fills up. The cache fills after about 12GB of writes, but since performance after the drop is steady at around 1.5GB/s the small cache isn't really a problem.

Average Throughput for last 16 GB	Overall Average Throughput

The WD Black SN750 offers best in class performance for long-duration sequential writes. After the SLC cache is full, the SN750 is about 5% faster than its predecessor for filling the rest of the drive. When looking at the total time to fill the drive, the SN750's advantage is slightly higher because its write speed to the SLC cache is also a bit faster.

BAPCo SYSmark 2018

BAPCo's SYSmark 2018 is an application-based benchmark that uses real-world applications to replay usage patterns of business users, with subscores for productivity, creativity and responsiveness. Scores represnt overall system performance and are calibrated against a reference system that is defined to score 1000 in each of the scenarios. A score of, say, 2000, would imply that the system under test is twice as fast as the reference system.

SYSmark scores are based on total application response time as seen by the user, including not only storage latency but time spent by the processor. This means there's a limit to how much a storage improvement could possibly increase scores, because the SSD is only in use for a small fraction of the total test duration. This is a significant difference from our ATSB tests where only the storage portion of the workload is replicated and disk idle times are cut short to a maximum of 25ms.

Our SSD testing with SYSmark uses a different test system than the rest of our SSD tests. This machine is set up to measure total system power consumption rather than just the drive's power.

The new WD Black SN750 regresses slightly in performance on SYSmark 2018, primarily on the responsiveness test, which is the subscore that's most sensitive to storage performance. The SN750 still clearly outperforms the WD Blue SATA SSD but even managed to fall behind the first-generation WD Black that used planar TLC and a third-party controller.

Energy Usage

The SYSmark energy usage scores measure total system power consumption, excluding the display. Our SYSmark test system idles at around 26 W and peaks at over 60 W measured at the wall during the benchmark run. SATA SSDs seldom exceed 5 W and idle at a fraction of a watt, and the SSDs spend most of the test idle. This means the energy usage scores will inevitably be very close. A typical notebook system will tend to be better optimized for power efficiency than this desktop system, so the SSD would account for a much larger portion of the total and the score difference between SSDs would be more noticeable.

The WD Black SN750 turns in an excellent energy consumption score, lower than any drive in this bunch save for the WD Blue SATA SSD.