Western Digital has discreetly launched an 8 TB version of its premium SN850X SSD, effectively doubling the top capacity within this esteemed drive family. While the new drive maintains similar performance metrics to its predecessors, it features twice the storage of the previous high-end model — accompanied by a considerable price increase due to its enhanced capacity.
Western Digital first unveiled its WD_Black SN850X SSDs in the summer of 2022, initially offering single-sided 1 TB and 2 TB models, as well as a double-sided 4 TB model. Nearly two years later, the company has deemed it appropriate to introduce an 8 TB model to serve as the flagship PCIe 4.0 SSD, thereby aligning with current NAND pricing trends and growing SSD capacity demands.
Similar to other SN850X models, the new 8 TB version utilizes WD’s in-house, 4-channel controller with a PCIe 4.0 x4 interface. As expected from a high-end SSD, the controller is paired with DRAM (DDR4) for page index caching, although WD has not disclosed the specific amount of DRAM per model. In terms of NAND, WD continues to use their BiCS 5 112L NAND, incorporating 4x 2 TB NAND chips, each containing 16 1Tbit TLC dies. This configuration doubles the NAND dies used on the 4 TB model.
The new 8 TB model boasts a peak read speed of 7,200 MB/sec, slightly below the performance of the 4 TB and 2 TB models due to the overhead from additional NAND dies. Peak sequential write speeds remain at 6,600 MB/sec, while 4K random write performance tops out at 1200K IOPS for both reads and writes. Although this is below the performance of current market flagship PCIe 5.0 SSDs, it’s noteworthy that the PCIe 5.0 controllers are still predominantly shipped by Phison, and higher capacities like 8 TB are not yet common.
The 8 TB SN850X also retains the same drive endurance rating as its SN850X counterparts. Doubling the NAND results in double the endurance of the 4 TB model, equating to 4800 terabytes written (TBW). In terms of drive writes per day, it maintains a 0.33 rating consistent with other SN850X drives.
| WD_Black SN850X SSD Specifications | ||||
| Capacity | 8 TB | 4 TB | 2 TB | 1 TB |
| Controller | WD In-House: 4 Channel, DRAM (DDR4) | |||
| NAND Flash | WD BiCS 5 TLC | |||
| Form-Factor, Interface | Double-Sided M.2-2280 PCIe 4.0 x4, NVMe |
Single-Sided M.2-2280 PCIe 4.0 x4, NVMe |
||
| Sequential Read | 7200 MB/s | 7300 MB/s | 7300 MB/s | 7300 MB/s |
| Sequential Write | 6600 MB/s | 6600 MB/s | 6600 MB/s | 6300 MB/s |
| Random Read IOPS | 1200K | 1200K | 1200K | 800K |
| Random Write IOPS | 1200K | 1100K | 1100K | 1100K |
| SLC Caching | Yes | |||
| TCG Opal Encryption | 2.01 | |||
| Warranty | 5 Years | |||
| Write Endurance | 4800 TBW 0.33 DWPD |
2400 TBW 0.33 DWPD |
1200 TBW 0.33 DWPD |
600 TBW 0.33 DWPD |
| MSRP (No Heatsink) | $850 | $260 | $140 | $85 |
Western Digital’s WD_Black SN850X is offered with and without an aluminum heatsink. The non-heatsink version aimed at laptops and BYOC setups is priced at $849.99, while the version with an aluminum heat spreader is available for $899.99. Both variants carry a significant price premium over the existing 4 TB model, which is readily available for $259.99.
Such a price premium is common for 8 TB drives and is expected to remain until both supply and demand rise enough to reduce prices. Nevertheless, with competing drives like Corsair’s MP600 Pro XT 8 TB and Sabrent’s Rocket 4 Plus 8 TB priced at $965.99 and $1,199.90 respectively, the introduction of the 8 TB SN850X is gradually pushing high-capacity M.2 SSD prices down. For systems equipped with multiple M.2 slots, purchasing two 4 TB SSDs remains the most cost-effective option.
