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WD Blue SN550 SSD Performance Reportedly Cut In Half When SLC Runs Out (Updated)

WD Blue SN550
WD Blue SN550 (Image credit: Western Digital)

Update 8/26/21 2:30pm PT: WD has issued the following statement to Tom's Hardware regarding the matter:

"In June 2021, we replaced the NAND in the WD Blue SN550 NVMe SSD and updated the firmware. At the time, we updated the product data sheet. For greater transparency going forward, if we make a change to an existing internal SSD, we commit to introducing a new model number whenever any related published specifications are impacted. We value our customers and are committed to providing the best possible solutions for their data storage needs."

Original Article:

Western Digital's Blue SN550 M.2 NVMe SSD, which is hailed as one of the best SSDs on the market, may be in danger of losing its spot. Chinese news outlet Expreview reportedly discovered that Western Digital may have swapped the flash on its Blue SN550 SSD, which negatively affects its performance when the SLC (single-level cell) cache is depleted.

The global semiconductor shortage is causing havoc in the computer hardware industry. Storage vendors, in particular, have resorted to modifying the recipe for their SSDs to deal with the component crisis. The current reality is that a SSD that just came out today may not employ the same parts further down the line since manufacturers are sourcing components from what's available. The problem occurs when the changes aren't communicated to consumers or expressed in the product sheets.

Big-name brands, including Adata, Patriot and more recently, Crucial have swapped the components from some of their most popular SSDs. It seems that Western Digital is the latest name to join the club, according to Expreview's findings.

Western Digital didn't immediately respond to a request for comment. This story will be updated if the company responds.

WD Blue SN550 Revisions

SSDFlash MemoryFirmware
WD Blue SN550 (New Revision)002031 1T00233010WD
WD Blue SN550 (Previous Revision)60523 1T00211070WD
WD Green SN350060947 1T00 231800WD

The WD Blue SN550 utilizes a WD controller (SanDisk 20-82-01008-A1) and SanDisk 96-layer BiCS4 3D TLC NAND flash with the 60523 1T00 part number. Expreview recently purchased a WD Blue SN550 that was manufactured on July 28, 2021. The publication noted that NAND flash on the new revision carries the 002031 1T00 part number.

Besides the dissimilarity in NAND flash, the new revision also comes with a different firmware. While the original WD Blue SN550 features the 211070WD firmware, the revised unit used the 233010WD firmware. Curiously, the WD Green SN350's firmware also start with 23.

The firmware for the previous and new revisions aren't interchangeable with each other. You can't flash the 233010WD firmware on a unit with the 211070WD firmware or vice versa. In fact, the Western Digital Dashboard software doesn't even pick up the 233010WD firmware for the older units. This seemingly tells us that something has changed on a hardware level. Since Expreview confirmed that the new revision still employs the SanDisk 20-82-01008-A1 SSD controller, the NAND flash is the only other possibility.

WD Blue SN550 Performance

SSDAverage Writes Without SLC Cache (MBps)Average Writes With SLC Cache (MBps)SLC Cache (GB)Total Capacity (GB)
SanDisk Ultra 1TB8491,94512931.1
WD Blue SN550 1TB (New Revision)3902,16012931.3
WD Green SN350 960GB3762,03010894.1

Expreview's TxBENCH benchmark results revealed that both revisions of the WD Blue SN550 deliver similar write performance as long as the SLC cache isn't filled up. The average write performance for the WD Blue SN550 was 2,160 MBps. Once the SLC cache runs out, the write performance dropped to 390 MBps. 

Although Expreview didn't provide the numbers for the previous revision, the outlet claimed a 50% performance hit. In our own tests, the original WD Blue SN550 hits 880 MBps in sustained write testing. The new revision, on the other hand, provides a write performance that just barely beats the inferior WD Green SN350 when both drives have their SLC caches occupied.

The NAND flash downgrade may not affect the average consumer since it's unlikely that the user will constantly fill the 12GB SLC cache. However, you'll certainly notice the lower performance if you move huge files a lot, such as 4K video files or big compressed archives. In any event, it doesn't excuse Western Digital for degrading the NAND.

  • PsyaNyde
    Phew, not that i'd notice, but I got the older version
    Reply
  • Mandark
    Can you spell junk?
    Reply
  • RodroX
    Is getting harder and harder to keep and eye for everything thats going on with this "part swapping".

    Similar to what Gigabyte did with its exploding PSU, getting stuff from anywhere (not testing a thing of course, I mean I wana believe they didn't test a thing) and then forcing costumers to buy their Frankestein along with for example a GPU... cough newegg, cough, cough.

    One start to wonder, What else is going on that we don't even know about it?
    Reply
  • hotaru251
    why i may pay more, but at least Samsung doesnt do this crap.
    Reply
  • plateLunch
    Well at least the pricing is fair. On Newegg, both the Blue 500 GB SN550 and Green 480 GB SN350 are priced at the same at $54.99.
    Reply
  • San Pedro
    hotaru251 said:
    why i may pay more, but at least Samsung doesnt do this crap.
    Yet....

    I helped a friend buy/build a PC on the weekend, and we ended up going with a Samsung 980 for a bit more over the SN500, and this makes that seem like a very wise choice, though he probably would never notice the difference in performance.
    Reply
  • Krotow
    At least WD Black seems not affected with this plague yet.

    hotaru251 said:
    why i may pay more, but at least Samsung doesnt do this crap.

    Not yet. If semiconductor shortages will continue in next year, who knows.
    Reply
  • ヴワル
    Well..., okay, just gotta stick to Samsung.
    Reply
  • Alvar "Miles" Udell
    Samsung 1TB 980 - $120
    SK Hynix Gold P31 1TB - $115
    WD 1TB Blue SN550 - $100

    Why would you have even considered the SN550 in the first place? The price difference between it, and the much better SK Hynix Gold P31 and the Samsung 980 is relatively miniscule, but the performance is so much better. There's not many places in a build where spending $15-$20 can result in a major performance increase.


    1TB Performance Results and Conclusion - Samsung 980 M.2 NVMe SSD Review: Going DRAMless with V6 V-NAND (Updated) | Tom's Hardware (tomshardware.com)
    Reply
  • cryoburner
    Alvar Miles Udell said:
    Why would you have even considered the SN550 in the first place? The price difference between it, and the much better SK Hynix Gold P31 and the Samsung 980 is relatively miniscule, but the performance is so much better. There's not many places in a build where spending $15-$20 can result in a major performance increase.
    In terms of real-world performance, not just some synthetic benchmarks, the vast majority of people won't perceive a performance difference between any of those drives. For most use cases, even a SATA SSD should provide very similar performance, as the system will typically be waiting on something other the storage device most of the time.

    Just look at the game load test for example. Who is going to notice a half-second difference in a 10 second load time between the Samsung 980 and the WD SN550? There's not going to be any perceptible difference there.

    Aside from things like copying large files or transferring them between two fast drives, the typical user is not likely to see a significant difference in transfer rates or responsiveness between any of these drives. And as that review points out, for large file writes that exceed the drive's cache, the (original) WD SN550 actually performed better at that metric, while the Samsung 980 dropped to around 430MB/s once its write cache was exceeded, meaning its sustained write performance was already similar to what the downgraded SN550 does.

    It could be argued that the 980 is a better drive overall, but it's highly unlikely that one would notice a "major performance increase" outside of certain benchmarks. Reviewers like to highlight the performance differences in synthetic tests in their reviews, but for common workloads, most SSDs tend to perform rather similar.
    Reply