WD Black SN850 and SN850X WD Black SN850 and SN850X

SN850X vs SN850: WD’s Flagship SSDs Compared

WD Black SN850 and SN850XIn 2022, the WD Black SN850X replaced the SN850 from 2020 as Western Digital’s flagship Gen4 M.2 SSD. Both are still suitable choices for high-end gaming PCs and PS5 consoles in 2023 and both are still widely available.

While the newer SSD lineup offers improvements in certain areas, the difference is by no means large enough to motivate an upgrade from a fully functioning SN850 SSD to an SN850X.

However, if you are choosing between the two for a new build, or to replace an older Gen3 or SATA SSD, it’s good to know how they differ. This is what we intend to explore on this page.

SN850X Vs. SN850: Specifications

First, there are some details worth noting in the official specs.

WD Black SN850 Specifications

WD Black SN850
Specifications
500GB1TB2TB
Form FactorM.2 2280M.2 2280M.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
ControllerProprietary
8-channel
Proprietary
8-channel
Proprietary
8-channel
DRAMLPDDR4LPDDR4LPDDR4
Memory96-layer
BiCS4 TLC
96-layer
BiCS4 TLC
96-layer
BiCS4 TLC
Sequential Read7,000 MB/s7,000 MB/s7,000 MB/s
Sequential Write4,100 MB/s5,300 MB/s5,100 MB/s
Random Read800K IOPS1M IOPS1M IOPS
Random Write570K IOPS720K IOPS710K IOPS
Endurance300 TBW600 TBW1,200 TBW
Warranty5-Year5-Year5-Year

Shopping links: Amazon, Newegg

The original SN850 uses 96-layer BiCS4 NAND memory chips of the TLC (triple-level cell) variety. These have been in production since 2018 and have been superseded by newer types. They offer solid performance nonetheless as well as excellent durability.

All capacities of the SN850 reach 7,000 MB/s in sequential read performance but differ in the sequential write and random IOPS areas. Interestingly, the 1 TB capacity is the fastest of the lot, with slightly better write performance than the 2TB model.

WD Black SN850X Specifications

WD Black SN850X
Specifications
1TB2TB4TB
Form FactorM.2 2280M.2 2280M.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
ControllerProprietary
8-channel
Proprietary
8-channel
Proprietary
8-channel
DRAMLPDDR4LPDDR4LPDDR4
Memory112-layer
BiCS5 TLC
112-layer
BiCS5 TLC
112-layer
BiCS5 TLC
Sequential Read7,300 MB/s7,300 MB/s7,300 MB/s
Sequential Write6,300 MB/s6,600 MB/s6,600 MB/s
Random Read800K IOPS1.2M IOPS1.2M IOPS
Random Write1.1M IOPS1.1M IOPS1.1M IOPS
Endurance600 TBW1,200 TBW2,400 TBW
Warranty5-Year5-Year5-Year

Shopping links: Amazon, Newegg

In the WD Black SN850X lineup, the TLC memory chips have been upgraded to 112-layer BiCS5. Performance has also improved somewhat and peaks with the 2TB and 4TB capacities.

SN850X Vs. SN850: Performance

For testing, we have on hand a 1TB WD Black SN850 and a 4TB SN850X. So, while this is not a 100% apples-to-apples comparison, it does represent peak performance from both lineups according to the specifications.

AS SSD

AS SSD performance chart WD Black SN850X Vs SN850

The SN850 manages slightly higher sequential read speeds in AS SSD (which admittedly is not very consistent), whereas the SN850X pulls ahead in the sequential write area.

CrystalDiskMark

CDM sequential performance chart WD Black SN850X Vs SN850

Sequential performance in CrystalDiskMark looks similar, but our SN850X takes the lead in terms of read speeds as well, albeit within the margin of error.

CDM random performance chart WD Black SN850X Vs SN850

Random performance with small files reflects many everyday workloads so it is an important metric. However, the difference is small compared to how it would look for two entirely different models.

Latency/Response Time

Anvil latency chart WD Black SN850X Vs SN850

We measure response times using Anvil’s Storage Utilities. Again, there is little difference between the SN850X and the SN850.

SN850X Vs. SN850: Gaming Performance

SSD performance in actual games is typically not hugely different between different models. Of course, the SN850X and SN850 share the same (or slightly tweaked version of the same) controller, so these drives should differ even less.

Final Fantasy 14 loading times comparison chart WD Black SN850X Vs SN850

In the standalone Final Fantasy 14: Shadowbringer benchmark, the SN850 was in fact slightly faster than the SN850X (although in fractions of a second and within the margin of error).

3DMark Storage chart WD Black SN850X Vs SN850

The 3DMark storage benchmark measures various gaming-related tasks such as installing, loading, and recording games. These results are more in line with what we would expect, with the SN850X taking the lead.

Conclusion

On average, the SN850X does offer slightly better performance compared to the SN850. However, the difference is typically small and the SN850 even manages to surpass the newer model by a hair in some specific tests. In real-world usage scenarios, like when loading games on a gaming PC or PS5, it is highly unlikely that these differences would be noticeable.

The WD Black SN850X and SN850 are both fast and dependable SSDs. But if prices are identical, you will likely want to opt for the newer SN850X.

Frequently Asked Questions

Yes, there is an onboard DDR4 DRAM cache/buffer on both the SN850X and SN850 SSDs.

For installation in the PS5, a heatsink is strongly recommended. It doesn't have to be a WD original, however. Gaming PCs typically have integrated motherboard heat spreaders, and in that case, a pre-installed heatsink is not needed.

You can use the SSDs without heatsinks or heat spreaders, but performance may throttle during intensive workloads if the device gets overheated.

SSD endurance ratings are specified as TBW (terabytes written or total bytes written) and these values are identical for the SN850 and SN850X lineups. For example, the 2TB models have an endurance rating of 1,200 TBW, meaning that you should be able to write 1,200 TB of data to the drive before memory cells become worn out. This is more than enough to last for the lifetime of most gaming PCs or consoles.

  1. The WD_BLACK SN850P is for PS5 but considering the heat generated by these SSDs, the Western Digital heatsink will be a good choice for PC too.

Leave a Reply

Your email address will not be published. Required fields are marked *