Western Digital is refreshing their NVMe-based WD Blue product line, replacing the WD Blue SN500 with the new WD Blue SN550. The SN550 updates both the controller and NAND, providing higher performance and capacity than the SN500.

The SN500 was Western Digital's first retail entry-level NVMe SSD, based on the OEM WD SN520. These drives use an in-house SSD controller based on the same architecture as the controller on their WD Black family (SN720/SN750), but with fewer channels, PCIe lanes and no external DRAM interface. The SN500 used the same PCB layout as the OEM SN520, which kept all the components within the first 30mm of the M.2 card, even though the SN500 is sold only as a M.2 2280 card rather than the variety of lengths the SN520 is available in.  

The SN500 impressed us with much better performance than we expected from a DRAMless NVMe SSD, and the power efficiency was also pretty good. The SN550 promises better performance enabled by a move up to four PCIe lanes, allowing sequential transfer speeds to now hit 2.4GB/s compared to 1.7GB/s for the SN500. That higher performance will drive power consumption up a bit, but considering that the SN500 rarely exceeds 2W, that's not a big problem for the SN550. However, WD is giving the SN550 an "improved thermal design" that appears to consist of just moving the NAND flash package to the far end of the M.2 card rather than keeping it right next to the controller. Even though the SN550 adds a 1TB option that the SN500 lacked, it still uses only one NAND flash package. That means that at least the 1TB model has to be using Western Digital's 512Gb TLC NAND dies.

WD Blue SN550 SSD Specifications
Capacity 250 GB 500 GB 1 TB
Form Factor M.2 2280 PCIe 3.0 x4
Controller WD in-house
NAND Flash Western Digital/SanDisk 96L 3D TLC
Sequential Read 2400 MB/s 2400 MB/s 2400 MB/s
Sequential Write 950 MB/s 1750 MB/s 1950 MB/s
Random Read 170k IOPS 300k IOPS 410k IOPS
Random Write 135k IOPS 240k IOPS 405k IOPS
Warranty 5 years
Write Endurance 150 TB
0.3 DWPD
300 TB
0.3 DWPD
600 TB
0.3 DWPD
MSRP $54.99 $64.99 $99.99

The WD Blue SN550 comes with the usual 5-year, 0.3 DWPD warranty, which is as good as can be expected for an entry-level drive. The initial MSRPs are on the high side, so these drives won't be reasonable purchases until prices come down a bit.

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  • RaduR - Tuesday, December 10, 2019 - link

    Why are you considering these expensive drives ? 100 USD / 1TB seems good value . Samsung QLC and Intel QLC are slower drives in the same price point .
  • Billy Tallis - Tuesday, December 10, 2019 - link

    Partly because my first source for prices had higher numbers than what WD has since posted on their own site (which is now reflected in the spec table). But partly because I remember what the sale prices were like last week, and I still want to see low-end NVMe drives undercutting high-end NVMe drives by more than just a few dollars.
  • deil - Tuesday, December 10, 2019 - link

    in my place Adata XPG SX8200 1 TB have roughly same performance numbers and is in 85'ish $ price point. Value is that its already tested and confirmed drive, not brand new with untested firmware.
  • Bulat Ziganshin - Tuesday, December 10, 2019 - link

    It has DRAM, so in a different league
  • Alistair - Tuesday, December 10, 2019 - link

    The Adata drive is much better. Faster by quite a bit.
  • TheJian - Thursday, December 12, 2019 - link

    Where the heck are you getting that price? Seems almost double that. That is why I bought the EX920 from HP for $114 though I would have bought it anyway (better drive IMHO feature wise).
  • twotwotwo - Tuesday, December 10, 2019 - link

    No mentions of HMB, which *seems* like it should be an easy win at the low end. (You know, if you don't have much DRAM, borrow some!) Out of curiosity have you formed much of an impression about whether HMB helps much, other things equal?
  • Billy Tallis - Tuesday, December 10, 2019 - link

    No HMB support here, as far as I can tell. WD puts several MB of SRAM cache on their controller, so HMB would be of limited use. The SN500's random IO performance is excellent when working with datasets of up to around 4GB, which is fine for an entry-level drive.
  • shabby - Tuesday, December 10, 2019 - link

    No dram.
  • -eth- - Friday, December 27, 2019 - link

    100 USD sounds really good for 1TB, but I have no idea why the pricing in Europe is that much higher. Even on the official WD store, it costs 145 EUR or 162 USD, while it's 100 in the US store. I understand that we have higher VAT and so on, but it's nowhere near high enough to warrant a 62% increase in the price. If it goes down to 100 EUR, then I'll consider buying one.

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