WD Black SN850 500GB NVMe SSD Review (2026)
The WD Black SN850 500 GB is a PCIe 4.0 NVMe SSD that still holds its own against newer drives, offering 7,000 MB/s sequential reads in a single-sided M.2 2280 form factor.
Controller & Memory
Under the hood, the SN850 runs WD's second-generation in-house NVMe controller (WD_BLACK G2), an Arm-based eight-channel design built on TSMC's 16nm FinFET process. It pairs that controller with Kioxia BiCS4 96-layer TLC NAND operating at Toggle DDR 3.0 speeds and a Micron DDR4 DRAM chip for the flash translation layer. The 500 GB variant uses 256Gb dies, and the entire PCB is single-sided, making it compatible with slim laptops and the PS5 expansion slot.
The SN850 was the first real hardware upgrade to WD's Black product line in over two years when it launched in late 2020. It competes directly against the Samsung 980 PRO and Phison E18-based drives in the high-end PCIe 4.0 segment. The 500 GB capacity is the entry point for this series and carries lower write specs than the 1 TB and 2 TB models. Also available in 1 TB and 2 TB capacities; the 1 TB variant reaches 5,300 MB/s writes and 720K random write IOPS, while the 500 GB drops to 4,100 MB/s and 570K respectively.
WD does not include a heatsink with the base model. A separate SKU adds an aluminium heatsink with RGB lighting, but independent reviewers found the bare drive runs acceptably cool with a motherboard M.2 heatsink. The SN850 lacks hardware-accelerated AES 256-bit encryption, a feature Samsung has offered for years on its high-end drives.
Storage Comparisons:
Black SN850 Performance & Benchmarks
The 500 GB WD Black SN850 is rated for up to 7,000 MB/s sequential reads and 4,100 MB/s sequential writes over its PCIe 4.0 x4 interface. Random performance reaches up to 800,000 read IOPS and 570,000 write IOPS. These numbers sit at the top of the PCIe 4.0 class for reads but represent a meaningful step down from the 1 TB model's 5,300 MB/s writes and 720K write IOPS, which is typical of smaller-capacity NVMe SSDs that have fewer NAND dies for parallel writes.
Western Digital Black SN850 500 GB vs M.2 4.0 x 4 peers
Switch between sequential throughput and random IOPS to see how this drive stacks up against other M.2 4.0 x 4 SSDs in our database. The highlighted bar is the drive on this page — click any other bar to open that drive.
- Patriot Viper PV593 1 TB: 14,500 MB/s read, 14,000 MB/s write
- Patriot Viper PV593 2 TB: 14,500 MB/s read, 14,000 MB/s write
- Patriot Viper PV593 4 TB: 14,500 MB/s read, 14,000 MB/s write
- Patriot Viper PV573 2 TB: 14,000 MB/s read, 12,000 MB/s write
- Western Digital Black SN850 500 GB (this drive): 7,000 MB/s read, 4,100 MB/s write
WD implemented a revised SLC caching scheme called nCache 4.0, which uses a hybrid dynamic and static SLC cache. On the 500 GB model, the dynamic cache spans roughly one-third of the available capacity, with a small static cache for quick recovery after heavy writes. Independent reviewers consistently report the SN850 delivers some of the most responsive real-world performance among PCIe 4.0 drives, with low latency in application benchmarks and game load times that are effectively indistinguishable from the Samsung 980 PRO. The drive can run warm under sustained heavy writes, so adequate airflow or a basic heatsink is advisable for workloads that push large files continuously.
Western Digital Black SN850 vs Competitors
See how the Black SN850 stacks up against other M.2 4.0 x 4 drives in our database:
Compare with rival drives:
Endurance, TBW & Warranty
WD rates the 500 GB SN850 for 300 TBW (terabytes written) of write endurance, backed by a five-year limited warranty that ends when either the TBW threshold or the five-year period is reached first. At a typical consumer write workload of 20 GB per day, 300 TBW translates to over 40 years of use, making endurance a non-issue for normal desktop and gaming scenarios. WD overprovisions the SN850 by approximately 9%, providing additional spare area for garbage collection and bad block management. The drive supports S.M.A.R.T. health monitoring through WD Dashboard, which also offers firmware updates and, on the heatsink model, RGB lighting control.
Western Digital Black SN850 500 GB Specifications
| Category | Value |
|---|---|
| Capacity [?] | 500 GB |
| Interface [?] | M.2 4.0 x 4 |
| Controller [?] | SanDisk 8-Channel |
| Memory type [?] | 96L Bics4 |
| DRAM [?] | DDR4 |
| Read speed (MB/s) [?] | 7000 |
| Write speed (MB/s) [?] | 4100 |
| Read IOPS [?] | 800000 |
| Write IOPS [?] | 570000 |
| Endurance (TBW) [?] | 300 |
| MTBF (million hours) [?] | 1.75 |
| Warranty (years) [?] | 5 |
Verdict: Is the Black SN850 Worth It in 2026?
The WD Black SN850 500 GB is a solid choice for builders who want PCIe 4.0 performance at the entry-level capacity of a premium product line. Its 7,000 MB/s reads and responsive real-world behavior make it suitable as a boot drive or game library on an AMD X570/B550 or Intel Z590+ platform. Content creators who regularly write large video files should consider stepping up to the 1 TB model, which offers significantly faster writes (5,300 MB/s) and double the endurance (600 TBW) for a modest price increase. Those who do not need PCIe 4.0 bandwidth can get comparable everyday responsiveness from cheaper PCIe 3.0 drives like the Samsung 970 EVO Plus or SK hynix Gold P31.
+ Pros
- 7,000 MB/s sequential reads
- Single-sided M.2 2280 fits PS5 and thin laptops
- DDR4 DRAM cache for consistent performance
- Large, fast-recovering nCache 4.0 SLC cache
- Five-year warranty
- 96-layer BiCS4 TLC NAND
- Cons
- 4,100 MB/s writes lag the 1 TB model by 1,200 MB/s
- No hardware-accelerated AES 256-bit encryption
- Can run warm under sustained heavy writes
- No included heatsink
- High idle power draw on desktop platforms
Buy this or similar SSD Storage:
Video Review
WD Black SN850 NVMe M.2 SSD - it's toasty!
