WD_Black SN770 Gen 4 SSD Review – Don’t Let Its Good Looks Fool You.

There is a long standing belief that buying a DRAM-less SSD is just wrong.  As much as this might hold water prior to and for those users not using Windows 10, it doesn’t for those looking for value and performance in storage today.  Without getting too complicated, NVMe and Windows 10 allow the SSD to create a Host Memory Buffer (HMB) which accesses DRAM memory rather than requiring the need for a DRAM Buffer chip as we normally see.  Most recently,  we reviewed the DRAM-less XPG Atom 50 and demonstrated how DRAM-less SSDs were gaining ground and performing up to the standards of their DRAM counterparts.

What if we went a step further and introduced you to the WD_Black SN770, an SSD built for gaming which actually surpasses some of the best gaming SSDs in the business?  What if we told you that this SSD is also a single-sided, single NAND chip DRAM-less design that only boasts performance up to 5GB/s?  Follow along; you might like what you see.

The WD-Black SN770 is a new release by Western Digital that will be available as of 2 February 2022 in capacities of 250GB, 500GB, 1TB and 2TB.  It is a PCIe 4.0 x4 (4-lane) single-sided 2280 form factor (80mm long) M.2 SSD that uses the latest NVMe 1.4 protocol.  Performance is listed at up to 5150MB/s read and 4900MB/s write with up to 800K IOPS for the 1TB sample on our test bench today, but decreases with lower capacities as might be expected.


Looking at the top of the SN770 itself, we see that it contains one SSD controller and one NAND memory chip.  The controller is a SanDisk in-house NVMe DRAM-less PCIe 4.0 4-channel SSD controller and the memory is KIOXIA  BiCS5 112-layer 3D TLC NAND flash memory.  That one NAND chip houses 1TB in memory.  WD boasts of advanced thermal management and our tests pushed this SSD as high as 72°C without a heatsink and no thermal throttling occurred during these tests. Testing with an aluminum heatsink brought the maximum temperature down to the mid-40s.


Admittedly, this SSD is an attractive single-sided design with only two chips of which the branding on the front is sized to fit perfectly between both.  MSRP pricing is listed at $59 (250GB), $79 (500GB), $129 (1TB) and $269 (2TB) with availability as of the posting of this report and this SSD does come with a 5-year warranty.  This will create an interesting sales point as we can guarantee the price for an SSD of this caliber has yet to come anywhere near as low as this SSD will.

Check WD_Black SN770 availability and pricing at Amazon.


Totally free for download here is the WD SSD Dashboard which has the ‘Game Mode’ feature that is exclusive to the SN750 and SN770 being tested.  This mode will require a restart when you turn it on and can be left on at all times if you choose.  From WD, turning Gaming Mode on will disable low power mode and keep the SSD running at peak levels for longer sustained execution when you want non-stop, consistent high performance.


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    Thanks for the test.

    So is the controller new? The one used in the WD850?
    Finally the BiCS5 nand! Can you disclose when you do the test of the upcoming WD850X?
    Will it be faster or slower? I guess the X means faster 😉

    Temperatures are nice indeed.
    Game loading shows that there is a flaw in performance. Due to the firmware? Maybe it can get better.
    The PCMark comparison is good, but as said on the test Cardea 440 Pro, your tests would benefit greatly with more real world testing instead of synthetic benchmarks.

    For this DRAM-cacheless ssd, I totally not know after what amount of GB the ssd starts to stumble and switch the pseudoCache from slc to mlc to tlc. That would be one of the important metrics to test for a dram-cacheless ssd I’d say, even when the target audience is a one that do not rank writing the whole disk in one sweep.
    What is the simultaneously mixed writing/reading-performance is,

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    If you have an older computer that doesn’t have any SSD, this will make it fly. I did a 5-minute install on my Dell G5000 Desktop and all the hard work was taken off of me because everything just fell into place! It’s so easy with how straightforward these parts are – installation could not be easier either; there were no problems at all after following some quick YouTube videos I found online (link). And best yet? Price wise M2 from reliable manufacturers can give your tired machine new life by boosting performance like never before while still saving money in comparison to buying another one outright which saves cash over time too.

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    I wanted to replace my old 128GB AData M.2 SATA system drive. The drive is plenty big enough but Passmark identified it as a huge bottleneck in my system (it is SATA after all).

    So, I found a 250GB WDB SN770 for $40CAD at Memory Express. I went into the store and the guy said that he had an even better deal for me.

    I managed to prevent my eyes from glazing over and, just to be polite, I allowed him to talk me up to a 500GB version (that was, for some reason, a faster drive) for just $5CAD more.

    They’re pretty good guys over there, eh? 😉

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