WD_Black SN850 PCIe 4.0 NVMe SSD Review – Vying For That Top Spot

Just when things seem to be shaping up in the world of SSDs, an unexpected entry always seems to appear.  This is the case with the Western Digital Black SN850 NVMe SSD we have on the bench today, and many might say that we really never saw this coming.  Like a freight train…  We were all just so excited to see Gen 4 storage hitting 7GB/s with Samsung and the up and coming Phison E18 controller that we totally overlooked the WD_Black Gen 4 SN850!

The Western Digital Black SN850 is a PCIe 4.0 (Gen 4) NVMe 1.4 M.2 SSD that is available in 500GB. 1 and 2TB capacities.  Specifications list this SSD as reaching 7GB/s read and 4100MB/s write with up to 800K IOPS for the 500GB capacity, 7GB/s read and 5.3GB/s write with up to 1 million IOPS for the 1TB capacity we are testing today, and 7.1GB/s read and 5.1GB/s write with up to a million IOPS for the 2TB capacity. Check Amazon pricing now.


The WD_Black SN850 comes with a 5-year limited warranty and has a TBW (Terabytes Written) rating of 300TBW for the 500GB, 600TBW for the 1TB and 1200TBW for the 2TB SSD.  MSRP Pricing is listed at $149.99 (500GB), $229,99 (1TB) and $449.99 (2TB) and checking Amazon, we are seeing it available up to 1TB with prices a bit higher than MSRP…but it is available to those that want one of the fastest storage devices available today.


Our WD Black SN850 is comprised of a black M.2 2280 (80mm) SSD which contains the SanDisk 8-channel Gen 4 PCIe 4.0 controller (named the WD Black G2), two pieces of proprietary 96-layer BiCS4 3D TLC NAND flash memory, and a 1GB DDR4 buffer.


The back of the SSD is void of any components and we are aware that the 2TB is one sided as well, which means that, if WD wanted, they could easily market a 4TB version of the SN850.  Last but not least, the WD_Black SN850 has a free copy of Acronis True Image available for data migration, as well as the WD Dashboard for maintaining the SN850 in optimal condition.  Both are available here.


This is the WD Dashboard, which is probably one of the most complete SSD tool kits available today.   Under the performance, it uses Windows Performance Monitor to monitor SSD speeds in real time.



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    The Real World File Transfer Comparison is amazing! I suspect that with some firmware tweaking they’ll speed up the music and photo transfer as well.
    A quote from your review:

    “Not only are the throughput and IOPS high sequentials looking very good, but also, low 4k random read and write throughput is solid.”

    This reminds me of one of the many reasons I bought a 512GB Crucial MX100, based on your review on June 12, 2014:


    “While such high IOPS are nice to see, most consumers should be looking at the 4K performance of the drive. High queue depth speed results over queue depths 3-5 usually don’t matter much for typical consumer desktop usage.”

    Right after you released this review, I built a new PC using the MX100 with all new components. I’m still using the MX100 (with all of the same components), but I plan on upgrading after we see finished-product E18 reviews, and AMD Zen3 CPUs become more plentiful.

    Since I’m one of the “typical consumer desktop” users, I still pay very close attention to the random 4K Q1T1. While I don’t know if this drive reviewed here is the fastest at random 4K, it still looks very good to me.
    In the meantime, I’m still stuck with a sequential read/write around 500 MB/s and random 4K read/write of 33.8 and 136.1 MB/s. My PC might be as slow as molasses compared to all of the new hardware, but it still works okay for being all 2014 hardware. I think I heard somewhere that patience is a virtue.
    Seriously though, it’s time to build a new PC with all new components, except for the case (Antec Solo).
    BTW, Crucial Storage Executive still reports that my MX100 is almost like new. It’s been a very dependable SSD.

    Thanks for another excellent review, Les.

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    @thessdreview staff: thanks for the review! When I checked the PCMark8 comparison chart I was a bit surprised that the Samsung 970 Pro 1TB is still ranked 2nd, while the 980 is tailing way behind. Any ideas why the difference between the two drives is that big?

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    Hi Les! Thanks for all the brilliant work. Really appreciate the info about the boot times of the ssd drives.
    I was rather astounded when I saw the info about the WD_Black SN850 PCIe 4.0.

    So I’d like to just check with you – when you refer to OS data/file sample – does it directly refer and relate to the boot times that you can get from the OS booting please?(hate slow boot times)

    Coz if it does, the WD_Black SN850 PCIe 4.0 is insane and thus the drive to get i guess…

    Do let me know please. Sincerely appreciate your reply! Thanks again Les!

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