Western Digital has quietly introduced an 8 TB version of its high-end SN850X SSD, doubling the top capacity of the well-regarded drive family. The new drive offers performance on par with other members of the range, but with twice as much capacity as the previous top-end model – and with a sizable price premium to go with its newfound capacity.

Western Digital introduced its WD_Black SN850X SSDs in the summer of 2022, releasing single-sided 1 TB and 2 TB models, along with a double-sided 4 TB model. But now almost two years down the line, the company has seen it fit to introduce the even higher capacity 8 TB model to serve as their flagship PCIe 4.0 SSD, and keep with the times of NAND prices and SSD capacity demands.

Like the other SN850X models, WD is using their in-house, 8-channel controller for the new 8 TB model, which sports a PCIe 4.0 x4 interface. And being that this is a high-end SSD, the controller is paired with DRAM (DDR4) for page index caching, though WD doesn't disclose how much DRAM is on any given model. On the NAND front, WD is apparently still using their BiCS 5 112L NAND here, which means we're looking at 4x 2 TB NAND chips, each with 16 1Tbit TLC dies on-board, twice as many dies as were used on the NAND chips for the 4 TB model.

The peak read speed of the new 8TB model is 7,200 MB/sec, which is actually a smidge below the performance the 4 TB and 2 TB models due to the overhead from the additional NAND dies. Meanwhile peak sequential write speeds remain at 6,600 MB/sec, while 4K random write performance maxes out at 1200K IOPS for both reads and writes. It goes without saying that this is a step below the performance of the market flagship PCIe 5.0 SSDs available today, but it's going to be a bit longer until anyone else besides Phison is shipping a PCIe 5.0 controller – never mind the fact that these drives aren't available in 8 TB capacities.

The 8 TB SN850X also keeps the same drive endurance progression as the rest of the SN850X family. In this case, double the NAND brings double the endurance of the 4 TB model, for an overall endurance of 4800 terabytes written (TBW). Or in terms of drive writes per day, this is the same 0.33 rating as the other SN850X drives.

WD_Back SN850X SSD Specifications
Capacity 8 TB 4 TB 2 TB 1 TB
Controller WD In-House: 8 Channel, DRAM (DDR4)
NAND Flash WD BiCS 5 TLC
Form-Factor, Interface Double-Sided M.2-2280
PCIe 4.0 x4, NVMe
Single-Sided M.2-2280
PCIe 4.0 x4, NVMe
Sequential Read 7200 MB/s 7300 MB/s 7300 MB/s 7300 MB/s
Sequential Write 6600 MB/s 6600 MB/s 6600 MB/s 6300 MB/s
Random Read IOPS 1200K 1200K 1200K 800K
Random Write IOPS 1200K 1100K 1100K 1100K
SLC Caching Yes
TCG Opal Encryption 2.01
Warranty 5 Years
Write Endurance 4800 TBW
0.33 DWPD
2400 TBW
0.33 DWPD
1200 TBW
0.33 DWPD
600 TBW
0.33 DWPD
MSRP (No Heatsink) $850 $260 $140 $85

Western Digital's WD_Black SN850X is available both with and without aluminum heatsink. The version without a heatsink aimed at laptops and BYOC setups costs $849.99, whereas a version with an aluminum heat spreader comes at $899.99. In both cases the 8 TB drive carries a significant price premium over the existing 4 TB model, which is readily available for $259.99.

This kind of price premium is unfortunately typical for 8 TB drives, and will likely remain so until both supply and demand for the high-capacity drives picks up to bring prices down. Still, with rival drives such as Corsair's MP600 Pro XT 8 TB and Sabrent's Rocket 4 Plus 8 TB going for $965.99 and $1,199.90 respectively, the introduction of the 8 TB SN850X is definitely pushing high-capacity M.2 SSD prices down, albeit slowly. So for systems with multiple M.2 slots, at least, the sweet spot on drive pricing is still to get two 4 TB SSDs.

Source: Western Digital

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  • Silver5urfer - Tuesday, July 16, 2024 - link

    SN850X has ton of issues. WDForum itself has a thread on it. Same with 980Pro and 990Pro awful firmware issues. On top these drives have poor endurance rating for their capacity. For eg 4TB MLC 860 Pro SATA SSD had over 4800TBW this 8TB TLC has less endurance than that.

    Even Sabrent PCIe3.0 drives had over 6000TBW for 4TB now with PCIe4.0 they dropped it to 3600 and their 8TB is 5400TBW. Samsung, WD, SKH all have worse than Sabrent.

    Enterprise TLC SATA has over 1.4PBW, that is 14000TBW that's a damn SATA drive. Now you consumers understand how garbage these new drives and technology are ? Simply going on that useless PCIe speed which will drop after 600-900Seconds and you don't even see any improvement in gaming. And don't even get started on Handbrake etc because very few even care about REMUXing or Transcoding and writing them onto SSD is not going to be easy esp NVMe.

    People should stop buying these overpriced SSDs which have poor reliability, M.2 is a weak standard. Enterprise uses SAS24Gbps which is more than PCIe4.0 M.2 and E1SS and the best U.2.

    Sadly the future is all QLC which is even worse garbage. Optane was killed by Intel prematurely as they released it at exorbitant pricing vs NAND and blew cash on stupid things and lost Lithography race and now losing the Silicon quality as well.
  • kn00tcn - Wednesday, July 17, 2024 - link

    when has the endurance rating ever matched reality?? nobody at time of manufacture or purchase would know how long any drive will last, most people dont even come close to reaching the rating anyway

    "overpriced" except msrp is not what ends up in the market, i got the 2tb 850x for only $135(+tax)CAD exactly a year ago on an almost week long sale, wildly different from the $hundred or more expensive msrp

    i'm still on b450 so stuck on pcie3 speeds, but at least the side effect is no need for heatsink and presumably less wear (heatsink model was more expensive, too)
  • ripsteakjaw - Saturday, July 27, 2024 - link

    A year ago every ssd was at least half what they're priced now if not more, I don't see how useful that is to anyone now.
  • kn00tcn - Wednesday, July 17, 2024 - link

    and yes i did see the firmware threads, but they seemed to mostly be coming from the first half year of production and also the non-X model, my firmware was already updated to/past the "good" one (probably why they had the huge sale in the first place)

    similarly i got an sn550 1tb a month after the scandal of them secretly swapping worse nand and performance, but mine had the old good nand (firmware version and benchmarks confirm it, plus i was able to personally compare to another sn550 from 2020 to double confirm)
  • ZeDestructor - Wednesday, July 17, 2024 - link

    If you're talking about the SN850X randomly not showing up after sleep/reboot, I have not had that happen to me ever in the year or so that I've owned mine.

    As for the 990 Pro's firmware fail, they found it, fixed it, and shipped the firmware update, so I don't see it as *that* much of a problem. Not with how underrated the published write endurance numbers are, anyways. What is somewhat disapponting is that Samsung ships the drives with ancient firmware on em from factory, so you have to remember to update em when you get em.

    On the topic of durability, it's well-known that consumer drives have hilariously small official endurance ratings, like the 1TB 850 Pro originally having an official 150TBW rating, and later revised to a just as hilariously low 600TBW. For 2LC 3D NAND (ie 40nm-class NAND).
  • GeoffreyA - Wednesday, July 17, 2024 - link

    SSDs are certainly faster, but even when copying files on a SATA drive, speed is not that grand. My 500 GB 860 EVO is *marginally* faster, in sustained copying, than my 4 TB hard disk, and an SMR one at that.
  • asktoomuch - Wednesday, July 17, 2024 - link

    Your arguments would have been way more convincing if you hadn't gone full rant and conflated separate and unrelated points.

    QLC vs TLC vs MLC vs SLC => this discussion is as old as SSDs and doesn't help anything

    NVMe vs SATA vs SAS => Face it, SAS is a data-center technology which will never be used in consumer hardware, not least because it doesn't bring anything to the average person and it has a higher cost.

    Writing endurance => most SSDs will see very little writes in their lifespan. The bulk of the usage is write once, read many. Not very relevant either.

    Buggy firmware => Unfortunately a real issue, but not a new one. Thankfully it is being addressed. And definitely nothing to do with NVMe. I remember my two SanDisk SSD Plus in 2013
    dying on me after 6 months because of a bad firmware. SanDisk fixed the issue and replaced my drives. I'm still using them today, 11 years later.

    It's a shame, because otherwise pointing that certain drives (SN850/SN850X and 980/990 Pro) have firmware issues could be useful to Anandtech's readership, but you discredit yourself with this senseless rant.
  • ballsystemlord - Thursday, July 18, 2024 - link

    As someone who owns an SSD, I have found that web browsers write quite a bit of data to their caches. I also suspect, from helping another user, that *coin applications also will do a lot of writes. We're talking in the 100s of GB/s a month.

    So yes, endurance matters. Just a few years ago, you could get (IIRC) about 1700TBW for a 1TB drive. Since then, manufacturers have really backed down on the specs. IDK why.
  • GeoffreyA - Thursday, July 18, 2024 - link

    I understand Silver5urfer's frustration. The prices seem to be going up and up, the quality down and down, and that becomes the new baseline. This technology has not replaced hard drives either. So, it is a bit of a disappointment. If we as consumers don't make a noise about it, these companies will get away with murder.
  • SanX - Thursday, July 18, 2024 - link

    asktoomuch, this is more knowledge, experience and anger at inferior tech or greed. Despite users specifically on workstations will get broken drive much before claimed 0.33 DWPD while paying for it (my two WD SN850X got problems at less than 0.05 DWPD in 3-4 years as i write less than 100GB per day, do the math), and others with light use will be OK, you call it "senseless rant". To me your post looks more like a rant when you essentially confirm all what he said.

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