WD Black SN850X with Heatsink 2TB SSD Review

1. Introduction2. WD Black SN850X + Heatsink3. Testing Methodology4. CrystalDiskMark5. ATTO Disk Benchmark6. AS SSD7. 128KB Sequential Performance8. 4K Random Read v QD Performance9. 4K Random Write v QD Performance10. 4K 70/30 Mixed Performance11. 4K Random Performance QD1-QD812. Throughput13. PCMark 10 Full System Drive Benchmark14. 3DMark Storage Benchmark 15. Performance Stability16. Temperatures17. Real Life File Testing18. Closing Thoughts19. View All Pages

The latest member of WD's Black product line of Gen 4 SSDs is the new SN850X, a successor to the popular Black SN850 that launched a couple of years ago. The new drive uses 112-layer NAND and an updated controller. WD sent us the Heatsink version of the drive, which also features RGB lighting.

The SN850X is (at the time of writing this review) available in three capacities; 1TB, 2TB and a flagship 4TB version. There's also a version of the drive with a heatsink fitted but only for the 1TB and 2TB models (it's the 2TB Heatsink equipped SN850X that we are looking at here). Incidentally, the original SN850 was available in three capacities as well at launch, but starting at 500GB and topping out with a 2TB model

The details surrounding the controller at the time of writing are very thin on the ground (as usual with a WD controller) but at a guess, it's probably an updated version of the in-house G2 controller used in the Black SN850 and the SN770 for that matter. This time around in conjunction with BiCS5 112-layer 3D TLC NAND rather than the 96-layer BiCS4 NAND of the SN850.

When it comes to performance, the SN850X is rated at up to 7,300MB/s for Sequential reads across the board, which is 300MB/s faster than the SN850. Sequential write performance is quoted as up to 6,600MB/s for the 2TB and 4TB models and up to 6,300MB/s for the 1TB drive. That's a very healthy 1,000MB/s increase over the 1TB SN850 while there's an even more impressive 1,500MB/s bump up for the 2TB SN850X over the SN850.

Random read performance for the 4TB and 2TB SN850X is quoted as up to 1.2M IOPS with the 1TB drive making do with 800,000 IOPS. The drive is rated at 1.1M IOPS for all three drives for random writes. As with the Sequential performance these figures are a good deal quicker than the SN850; 2TB & 1TB 1M IOPS random reads, 2TB 710,000 IOPS & 1TB 720,000 IOPS random writes.

Endurance ratings for the SN850X are; 4TB 2,400TBW, 2TB 1,200TBW and 600TBW for the 1TB drive. The 1TB and 2TB figures are the same as the previous SN850. WD backs the drive with a 5-year warranty.

Physical Specifications:

• Usable Capacities:  2TB.
• NAND Components: BiCS5 -112-layer 3D TLC.
• NAND Controller: WD.
• Cache: 2GB LPDDR4.
• Interface: PCIe Gen 4 x4, NVMe 1.4.
• Form Factor: M.2 2280.
• Dimensions: 80 x 23.4 x 8.8mm.
• Drive Weight: 24g.

Firmware Version: 620281WD.

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