WD Black SN8100 SSD review: Fantastically fast, frustratingly inconsistent

At a glance

Expert's Rating

Pros

Extremely fast synthetic benchmark results — at times
DRAM for excellent random performance
5-year, 600TBW warranty

Cons

Write speeds varied from 300MBps to 13GBps on our usual test bed
Pricey

Our Verdict

This fantastically speedy PCIe 5.0 SSD will deliver the 14GBps goods. But it had compatibility issues on our test bed with write speeds all over the place — as high as the advertised 13GBps, but as low as 300MBps.

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With WD’s 8TB Black SN850X being our top-rated PCIe 4.0 SSD, and the WD Black SN7100 holding sway as the second-ranked HMB (host memory buffer) PCIe 4.0 SSD, I was expecting great things from the company’s latest: the PCIe 5.0 WD Black SN8100. Well, I got great things, but also some not-so-great things — for reasons that remain unclear.

Note that I will revisit this review if and when the “things” situation (read the performance section) with the SN8100 clears up. Also, it seems Sandisk, after a recent “split” from WD, is now marketing WD drives — i.e., this is the Sandisk WD Black SN8100.

Read on to learn more, then see our roundup of the best SSDs for comparison.

What are the WD Black SN8100’s features?

The WD Black SN8100 is a PCIe 5.0, NVMe 2.0, 2280 (22mm wide, 80mm long) M.2 SSD. It uses stacked BiCS8 TLC NAND and a Sandisk controller plus DRAM for fast random operations.

Sandisk provides a five-year warranty on the WD Black SN8100, mitigated by a 600TBW-per-terabyte-of-capacity rating — in other words, if you write more than 600TB to the drive, it may go into read-only mode and the warranty is void at that point.

Note that most SSDs are good for far more writes than their rating, and it’s unlikely you’ll write anywhere near that much in even 10 years.

How much does the WD Black SN8100 cost?

Sandisk sells the WD Black SN8100 in three capacities: 1TB for $180, 2TB (tested) for $280, and 4TB for $550. That’s more than the Samsung 9100 Pro and the equally fast Crucial T705 (which are both on sale for $170 and $142, respectively, at the time of this writing), but in the same ballpark as their MSRPs. I’d expect the SN8100 to settle in at a competitive price. All things being equal, that would make it a good value, but…

How does the WD Black SN8100 perform?

When operating correctly, the SN8100 was right up there with its fastest PCIe 5.0 competitors. However, hot on the heels of the Sandisk Extreme Pro SSD with USB4 (that’s the actual name) not always connecting at full speed, I experienced a somewhat similar issue with the WD Black SN8100. Albeit only with writes.

When using the same M.2/PCIe 5.0 slot with which I’ve successfully tested all NVMe SSDs over the last two years, the 8100 initially performed up to snuff. Subsequently, however, write speeds in synthetic benchmarks dropped to 2GBps/PCIe 3.0 levels, and then mysteriously to 600MBps/SATA levels and even lower.

The phenomenon was also wildly inconsistent: One day performance was as expected, the next day it would fall off the planet. Reboots would seem to cure the issue, then it would reappear.

This is not the write speed you want from a PCIe 5.0 SSD. The SN8100 sometimes wrote at 13.5GBps but sometimes dropped as low as 300MBps. Go figure.

Moving the WD Black SN8100 to a ROG PCIe 5.0/NVMe adapter card nestled in the test bed’s sole PCIe 5.0 slot, write performance consistently reached expected levels — tracking without fail at 13.5GBps in all the synthetic benchmarks.

Thermals were not an issue as the SN8100 never cracked 50 degrees Celsius. However, Sandisk touts the drive’s outstanding energy savings, so maybe there’s another reason for it throttling down writes, which require far more energy than reads.

One day performance was as expected, the next day it would fall off the planet.

I retested the two competing drives, Crucial’s frantastic T705, and Samsung’s blazing 9100 Pro on the adapter card, but both performed slightly worse, so the numbers on the charts are from the original tests in the usual M.2 slot. No need to punish them for WD/Sandisk’s issue.

With those caveats, the SN8100 did quite well, even taking the top spot in a couple of tests.

With the inconsistency caveat, the SN8100 did quite well. Even taking the top spot in a couple of tests.

Once again, the SN8100 was right up there with its competitors and even managed two first places in CrystalDiskMark 8’s random tests.

Our 48GB transfer tests had the SN8100 falling slightly behind the competition. Not by much, but still just outside of the margin of error.

The SN8100 again lagged behind the other two drives in the real-world 450GB write test, though not by a lot. Note that the top-performing drives in this test are almost all HMB (host memory buffer) designs. And mostly PCIe 4.0. Go figure.