WD Black SN8100 SSD Review: A Speedy Performer With Compatibility Caveats

Western Digital’s WD Black SN850X already reigns supreme as our top PCIe 4.0 SSD, and the WD Black SN7100 holds its own as the second-best HMB PCIe 4.0 SSD. Thus, I had high expectations for the company’s new PCIe 5.0 offering, the WD Black SN8100. While the SN8100 delivered in some aspects, its performance was marred by some unexpected compatibility issues, which left me with a mixed impression. I plan to revisit this review if WD or Sandisk resolves the performance inconsistencies with the SN8100.

The WD Black SN8100 is a PCIe 5.0, NVMe 2.0, 2280 M.2 SSD. It utilizes stacked BiCS8 TLC NAND and a Sandisk controller, along with DRAM for faster random operations. The drive boasts a five-year warranty, limited by a 600TBW-per-terabyte-of-capacity rating. Exceeding this write limit may render the warranty void and could potentially trigger read-only mode. However, most SSDs typically handle far more writes than their rated TBW, making it unlikely that most users will reach this limit within the warranty period.

Sandisk currently offers the WD Black SN8100 in three capacities: 1TB for $180, 2TB (the model tested) for $280, and 4TB for $550. While the prices are higher than the current sale prices of the Samsung 9100 Pro and Crucial T705, they’re similar to the MSRPs of those drives. I anticipate the SN8100’s price to become more competitive in the future. If its price aligns with its performance, it would represent a good value, assuming the compatibility issues can be resolved.

When functioning correctly, the SN8100 rivaled the fastest PCIe 5.0 SSDs on the market. However, following the issues encountered with the Sandisk Extreme Pro SSD with USB4, which occasionally failed to connect at full speed, I experienced similar, but different, problems with the WD Black SN8100, specifically with write speeds.

Initially, the SN8100 performed admirably when tested in the same M.2/PCIe 5.0 slot that has been successfully used for testing numerous NVMe SSDs over the past two years. However, write speeds in synthetic benchmarks subsequently dropped to PCIe 3.0 levels of approximately 2GBps and then further to SATA levels of 600MBps or even lower.

This performance degradation was inconsistent. On some days, the drive performed as expected, while on others, its write speeds plummeted. Rebooting the system temporarily resolved the issue, but it invariably reappeared.

To isolate the issue, I moved the WD Black SN8100 to a ROG PCIe 5.0/NVMe adapter card in the test bed’s PCIe 5.0 slot. With the adapter card, write performance consistently reached expected levels, maintaining 13.5GBps in all synthetic benchmarks. Thermals were not an issue, as the SN8100 never exceeded 50 degrees Celsius.

Sandisk promotes the drive’s energy efficiency, leading to the possibility that the write throttling may be related to power management. Write operations require more power than reads, potentially causing the drive to reduce performance to conserve energy.

To ensure fairness, I retested the Crucial T705 and Samsung 9100 Pro, both competitive PCIe 5.0 SSDs, on the adapter card. However, their performance slightly decreased compared to their initial tests in the M.2 slot. To avoid penalizing them for WD/Sandisk’s compatibility issue, the performance charts reflect the original test results obtained in the standard M.2 slot.

With these caveats, the SN8100 performed well in testing. In a few tests, it even claimed the top spot.

In CrystalDiskMark 8’s random tests, the SN8100 rivaled its competitors, even achieving the highest scores in two tests.

However, in our 48GB transfer tests, the SN8100 slightly lagged behind the competition, although not significantly.

The SN8100 also trailed in the real-world 450GB write test, but the difference was minor. Notably, the top-performing drives in this test are primarily HMB (host memory buffer) designs, mostly PCIe 4.0 SSDs.

Despite its slightly slower performance in real-world transfer tests, the SN8100 remains a remarkably fast SSD. The issues encountered with our motherboard’s M.2 slot remain unexplained.

A lengthy conversation with Sandisk failed to shed light on the issue, as the company was unable to replicate the problem, and a second SN8100 exhibited the same behavior.

While the issue remains unclear, I suspect it could stem from motherboard/drive incompatibility, which most users are unlikely to encounter. However, I cannot guarantee this, so I recommend running CrystalDiskMark 8 multiple times after booting to verify performance before the return window closes. Identifying subtle SSD slowdowns can be difficult, especially given the inconsistency of the issue.

The WD Black SN8100 is among the fastest NVMe SSDs in synthetic benchmarks that I have tested. However, I must advise prospective buyers to check compatibility using CrystalDiskMark 8 or similar tools before committing to a purchase.

I plan to update this review if a solution to the write performance mystery emerges or if the situation changes.

Our storage tests are conducted on a system running Windows 11 (22H2) 64-bit with a Z790 (PCIe 5.0) motherboard and an i5-12400 CPU, paired with two Kingston Fury 32GB DDR5 modules (64GB total memory). We use integrated Intel graphics. The 48GB transfer tests utilize an ImDisk RAM disk occupying 58GB of memory. The 450GB file is transferred from a Samsung 990 Pro 2TB SSD that also hosts the operating system.

Each test is performed on a newly formatted and TRIM’d drive to ensure optimal results. Note that SSD performance typically decreases as the drive fills up, due to reduced NAND available for secondary caching and other factors.

The performance data presented applies only to the specific drive we tested and the tested capacity. SSD performance can vary by capacity, depending on the number of chips and the amount of NAND used for secondary caching. Vendors may also occasionally change components. If you observe significant discrepancies between your own experience and our reported performance, please notify us, assuming your system configuration is similar.