The Western Digital WD Black SN850 Review: A Very Fast PCIe 4.0 SSD
by Billy Tallis on March 18, 2021 12:50 PM ESTConclusion
The Western Digital WD Black SN850 has clearly established itself as a premium consumer SSD. It trades the lead with the Samsung 980 PRO on many tests but beats Samsung more often than not, making the WD Black SN850 the fastest PCIe 4.0 SSD we have tested so far.
Western Digital was slow to get into the NVMe game and at times it has seemed like they weren't trying very hard to go after the high end. But they're definitely serious contenders now. The high-end consumer SSD market is no longer just Samsung and the runners-up.
Overall the SN850 does have a few performance quirks, but no serious weaknesses to worry about. The SN850 has a bigger and faster SLC cache than most of the competition and generally seems better-optimized for client workloads than the 980 PRO.
The SN850 also tends to have a bit better power efficiency than the 980 PRO, though the SN850 can definitely end up drawing a lot of power to deliver such high performance. Western Digital has sacrificed some of the efficiency from their previous-generation drives, so the heatsink option makes more sense than it did for the SN750. But the heatsink should be no means be viewed as mandatory. Only the most intense niche workloads will be able to keep the SN850 busy long enough for thermal throttling to become a serious limitation.
Samsung and Western Digital are also facing stiff competition from numerous brands that are using the Phison E18 SSD controller. We don't have full benchmark results from any of those yet, but preliminary results indicate that while there may be no clear winner for the absolute fastest consumer SSD, the Western Digital SN850 is holding on to most of its individual benchmark wins. Later this year we're expecting another wave of Phison E18 drives to arrive using 176L 3D TLC NAND, which may shift the balance.
Some enthusiasts have bemoaned the switch away from MLC NAND (2 bits per cell) for high-end drives. But the WD Black SN850 shows that high-end TLC (3 bits per cell) drives now match or surpass the performance of the Samsung 970 PRO on almost every single metric, even the corner cases where the TLC+SLC caching strategy traditionally runs into trouble. The only remaining test where that last high-end MLC drive still has a significant advantage is sustained sequential write speed after any SLC cache has been filled. For the very narrow range of workloads where that might matter more than the significantly higher peak performance modern consumer TLC drives offer, there are plenty of enterprise TLC drives that don't use SLC caching at all.
MLC is now dead, and there's no compelling reason to bring it back (except for niche applications).
| Premium NVMe SSD Price Comparison March 18, 2021 |
|||||||
| 500 GB | 1 TB | 2 TB | 4 TB | ||||
| WD Black SN850 (without heatsink) |
$119.99 (24¢/GB) | $199.74 (20¢/GB) | $379.99 (19¢/GB) | ||||
| ADATA XPG Gammix S70 | $199.99 (20¢/GB) | $399.99 (20¢/GB) | |||||
| Corsair MP600 PRO (Phison E18) |
$224.99 (22¢/GB) | $434.99 (22¢/GB) | |||||
| Sabrent Rocket 4 Plus (Phison E18) |
$199.99 (20¢/GB) | $399.98 (20¢/GB) | $799.99 (20¢/GB) | ||||
| Samsung 980 PRO | $119.99 (24¢/GB) | $196.74 (20¢/GB) | $379.99 (19¢/GB) | ||||
| Inland Performance (Phison E16) |
$94.99 (19¢/GB) |
$178.99 (18¢/GB) | $329.99 (16¢/GB) | ||||
| Sabrent Rocket 4.0 (Phison E16) |
$89.99 (18¢/GB) |
$149.98 (15¢/GB) | $299.98 (15¢/GB) | ||||
| PCIe 3.0: | |||||||
| SK hynix Gold P31 | $74.99 (15¢/GB) |
$134.99 (13¢/GB) | |||||
| WD Black SN750 | $62.99 (13¢/GB) |
$138.08 (14¢/GB) | $299.99 (15¢/GB) | ||||
| Samsung 970 EVO Plus | $79.99 (16¢/GB) |
$164.99 (16¢/GB) | $319.99 (16¢/GB) | ||||
The top-tier PCIe 4.0 SSDs are all priced very similarly right now, accurately reflecting that they all provide about the same real-world performance. Western Digital's current pricing for the WD Black SN850 is definitely competitive in this context. For a lot of consumers shopping in this segment, the decision may come down to heatsink options and aesthetics. The older, somewhat slower and less efficient generation of PCIe 4.0 SSDs based on the Phison E16 controller includes some much more affordable drives that are only a bit more expensive than the top PCIe 3.0 SSDs.
For most use cases a PCIe 4.0 SSD is still definitely overkill as it won't offer meaningfully better real-world performance than a good PCIe 3.0 SSD. PCIe 4.0 SSDs are still largely lacking their killer app, and saving something like $65 on a 1TB drive to drop down to PCIe 3.0 definitely has an impact on the rest of a system build's budget. But for consumers that are convinced they have good reason to upgrade to PCIe 4.0 storage, the WD Black SN850 is worthy choice. It offers the satisfaction and bragging rights of one of the fastest drives available, and will not be significantly outclassed until PCIe 5.0 arrives.
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Samus - Tuesday, March 23, 2021 - link
eva: true. SATA hasn't been updated in over a decade (unlike SAS) and it'll be some time before consumer-class drives can saturate a 6Gbps link (currently almost none can even saturate a 3Gbps link.)With MAMR, HAMR, etc coming to market, performance is finally going to increase where areal density was historically the only way sequential transfers went up, so drives might start cracking SATA2 bandwidth. I suspect when drives near SATA3 bandwidth, it'll either be so long from now that hard disk technology in the consumer space will be dead (replaced by cheap NAND storage) as hard disk technology seems to be focusing on data centers where SAS is common and already capable of 12Gbps+, or consumers that wish to actually use magnetic disk storage will adopt SAS.
Molor1880 - Thursday, March 18, 2021 - link
2.5 in drives and U.X won't make a comeback outside a server room, which is what that combination is designed for. The trend for personal devices is smaller and lighter, not bigger and bulkier. I would expect M.2 and gum stick drives to evolve, in step with PCIe, but it's not going away for at least another decade.Tomatotech - Thursday, March 18, 2021 - link
2.5” is dead for casual home use. I used to think it had a place in the office, but with the rise of laptop-powered WFH and the popularity of space-saving small SFF computers for the office I don’t see it as having a future.Your point about cost makes no sense. 2 TB+ of SSD chips is expensive. It makes no difference whether it’s on an m.2 stick or in a half empty U.3 case, it costs the same either way. With U.3 there’s a (small) extra cost for the packaging, plus the extra wires and extra ports required and extra assembly steps. Might be worth it in the datacentre but not for price-sensitive home or office market where 99% of drives are never swapped.
Tomatotech - Thursday, March 18, 2021 - link
Ninja’d by Molor1880!WaltC - Thursday, March 18, 2021 - link
I think M.2 is here to stay. You are looking for economies of scale in NVMe M.2 drive capacity--that will happen as time goes on. It's remarkable to me how fast M.2 drives have ratcheted up in performance and capacity already. But, hey, if you need the economic capacity there's always the old 7200 rpm standby, right? These super-capacity drives will be around for a long while--but eventually M.2 will supplant them, imo.My older PCIe3 960 EVO M.2 boot drive would throttle regularly in large tasks, like doing a full AV Defender scan on C:\. The drive always crashed and never completed a full C:\ scan. This doesn't happen with the 980 Pro at all, and it's running in the same mboard and in the same slot the 960 ran in--using the same heatsink--just a flat sink that came with the mboard. Things are improving rapidly on the NVMe M.2 front, imo.
damianrobertjones - Friday, March 19, 2021 - link
"Threw is the past tense of the verb throw. It’s the word you use to say that something threw you for a loop or threw you off. Through is an adverb and a preposition. It’s used to say that you entered on one side of something and exited on the other."Not sure if 2.5" drives have gone anywhere?
twotwotwo - Wednesday, April 21, 2021 - link
There are a few 4 and 8TB m.2 drives out already, so a stick with more than 2TB might be practical for you before any switch to the mostly-enterprise u.3 form factor. Not that there's anything wrong with holding on to your current stuff! :)Makaveli - Thursday, March 18, 2021 - link
"Later this year we're expecting another wave of Phison E18 drives to arrive using 176L 3D TLC NAND"This is what i'm waiting to see.
I don't like that all the new generation drives also all took a reduction in TBW and all seem to have smaller SLC caches minus this WD drive.
ozzuneoj86 - Thursday, March 18, 2021 - link
With the SK Hynix P31 performing so well for the money, especially in efficiency, I'll be keeping an eye out for PCI-E 4.0 offerings from them.I'm currently booting from a 2.5" MX500 1TB. Since I have an X570 board, it feels like my next drive purchase should be PCI-E 4.0. Thankfully, I doubt these things provide any appreciable difference in performance over a good SATA SSD for the vast majority of applications I use, so I can stand to wait for the prices to come down. Given the choice between buying a 1TB SSD with blistering fast performance for $200, or one that generally benchmarks lower but uses less power, runs cooler and provides an almost identical experience for $135 (with sales often much lower)... its hard to justify the more expensive one.
lmcd - Thursday, March 18, 2021 - link
Imo in a laptop it's impossible to justify a faster SSD that consumes more power.In a desktop, though, I can see it making sense for certain workloads.