Jesper Berg 
Western Digital caters to gamers and enthusiasts with its WD Black lineup. However, there are not only multiple generations of these M.2 NVMe SSDs now but also multiple tiers – let’s call them high-end and midrange.
The WD Black SN850 is a high-end PCI-Express 4.0 (Gen4) SSD that was class-leading at the time of launch (February 2021). Although it has now been superseded by the updated SN850X (see our comparison of these two SSDs here), it is still among the fastest of its kind.
WD’s SN770, on the other hand, arrived one year later and did not aim for the top of the performance charts. It instead occupies a more affordable midrange tier among other SSDs with no onboard DRAM buffer. Can it still challenge the SN850?
SN850 Vs. SN770: Specifications
To keep things reasonably simple, this table compares the 2TB capacities of the SN770 and SN850. Scroll to the bottom of this page for full specifications of the entire lineups.
Last update on 2024-04-28 / Affiliate links / Images from Amazon Product Advertising API
Even if the WD Black SN770 was launched a year later than the SN850, the latter is Western Digital’s flagship-level M.2 SSD from the previous generation. It uses onboard DRAM to speed up transfer rates and its maximum sequential performance approaches the upper boundaries of the PCIe Gen4 x4 interface bandwidth.
That being said, the SN770 is very fast for a DRAM-less SSD and also comes with a newer generation of NAND flash memory chips. It is also important to note that maximum sequential transfer rates are not the only factor that affects real-world performance. In fact, it is decidedly less important than random performance and latency in everyday workloads.
SN850 Vs. SN770: Synthetic Performance
Note that our testing was conducted using the 1TB version of the WD Black SN850 and the 2TB model of the SN770. This is a slight advantage for the SN850, as the 2TB SN770 is rated as being marginally slower than the 1TB capacity.
AS SSD
In AS SSD – a popular benchmark that uses incompressible data – the SN850 offers about 23% better sequential read performance and 36% better write performance, respectively, than the WD Black SN770.
CrystalDiskMark
The SN850 and SN770 are quite evenly matched when measuring sequential write performance with CrystalDiskMark, but the SN850 pulls ahead by almost 30% in the corresponding read benchmark.
Interestingly, the tables are turned in favor of the DRAM-less SN770 with 4K random data at the important Q1T1 (minimum) queue depth. It’s a small but noteworthy difference of about 9%.
Latency/Response Time
Latency (measured with Anvil’s Storage Utilities) as measured in microseconds is also similar with the two drives, although the WD Black SN850 is measurably faster in the read area.
SN850 Vs. SN770: Gaming Performance
Gaming tests are always interesting – and even more so with hardware that explicitly targets gamers.
The 1TB WD_Black SN850 remains the fastest SSD we’ve ever tested in the FF XIV: Shadowbringer standalone benchmark. It even beats the SN850X and Samsung 990 Pro by a hair. It’s also 21% faster than the 2TB SN770.
The 3DMark Storage benchmark result is more in line with what we would expect, with the SN850 being less than 10% faster than the SN770.
Although it is below Sony’s recommended minimum specs for slotting into the PS5, the SN770 will still work, but equipping it with a 3rd-party heatsink is likely a good idea. The SN850 is nevertheless better suited for the PlayStation 5 and is also available with an optional pre-attached heatsink.
Conclusion
In the second half of 2023, the SN850 is becoming increasingly hard to find as it has been sold out to make way for the SN850X. The newer model is a bit faster overall, but not by noticeable amounts. Both of them are however faster than the WD Black SN770, which in turn is much faster than the SN550 and other Gen3 drives.
Read more:
- Comparison of the WD_Black SN770 Vs SN850X
- Comparison of the WD_Black SN850X Vs. SN850 (non-X)
- Comparison of the WD_Black SN770 Vs. SN550
- Full review of the SN770
- Full review of the SN850X
- Updated listing of the fastest M.2 SSDs
- Updated listing of the fastest SSDs overall (incl. SATA)
SN770 Series: Full Specifications
| WD Black SN770 | 250GB | 500GB | 1TB | 2TB |
|---|---|---|---|---|
| Form Factor | M.2 2280 | M.2 2280 | M.2 2280 | M.2 2280 |
| Interface / Protocol | PCIe 4.0 x4 / NVMe 1.4 | PCIe 4.0 x4 / NVMe 1.4 | PCIe 4.0 x4 / NVMe 1.4 | PCIe 4.0 x4 / NVMe 1.4 |
| Controller | Proprietary | Proprietary | Proprietary | Proprietary |
| DRAM | No | No | No | No |
| Memory | 112-Layer TLC | 112-Layer TLC | 112-Layer TLC | 112-Layer TLC |
| Sequential Read | 4,000 MB/s | 5,000 MB/s | 5,150 MB/s | 5,150 MB/s |
| Sequential Write | 2,000 MB/s | 4,000 MB/s | 4,900 MB/s | 4,850 MB/s |
| Random Read | 240K IOPS | 460K IOPS | 740K IOPS | 650K IOPS |
| Random Write | 470K IOPS | 800K IOPS | 800K IOPS | 800K IOPS |
| Endurance | 200 TBW | 300 TBW | 600 TBW | 1,200 TBW |
| Warranty | 5-Years | 5-Years | 5-Years | 5-Years |
| MSRP | $59.00 | $79.00 | $129.00 | $269.00 |
SN850 Series: Full Specifications
| WD Black SN850 | 500GB | 1TB | 2TB |
|---|---|---|---|
| Form Factor | M.2 2280 | M.2 2280 | M.2 2280 |
| Interface / Protocol | PCIe 4.0 x4 / NVMe 1.4 | PCIe 4.0 x4 / NVMe 1.4 | PCIe 4.0 x4 / NVMe 1.4 |
| Controller | Proprietary | Proprietary | Proprietary |
| DRAM | 512 MB DDR4 | 1 GB DDR4 | 2 GB DDR4 |
| Memory | 96-Layer TLC | 96-Layer TLC | 96-Layer TLC |
| Sequential Read | 7,000 MB/s | 7,000 MB/s | 7,000 MB/s |
| Sequential Write | 4,100 MB/s | 5,300 MB/s | 5,100 MB/s |
| Random Read | 800K IOPS | 1M IOPS | 1M IOPS |
| Random Write | 570K IOPS | 720K IOPS | 710K IOPS |
| Endurance | 300 TBW | 600 TBW | 1,200 TBW |
| Warranty | 5 Years | 5 Years | 5 Years |
| MSRP | $149.00 | $230.00 | $450.00 |
