Western Digital has quietly introduced an 8 TB version of its high-end SN850X SSD, doubling the top capacity of the well-regarded drive family. The new drive offers performance on par with other members of the range, but with twice as much capacity as the previous top-end model – and with a sizable price premium to go with its newfound capacity.
Western Digital introduced its WD_Black SN850X SSDs in the summer of 2022, releasing single-sided 1 TB and 2 TB models, along with a double-sided 4 TB model. But now almost two years down the line, the company has seen it fit to introduce the even higher capacity 8 TB model to serve as their flagship PCIe 4.0 SSD, and keep with the times of NAND prices and SSD capacity demands.
Like the other SN850X models, WD is using their in-house, 8-channel controller for the new 8 TB model, which sports a PCIe 4.0 x4 interface. And being that this is a high-end SSD, the controller is paired with DRAM (DDR4) for page index caching, though WD doesn’t disclose how much DRAM is on any given model. On the NAND front, WD is apparently still using their BiCS 5 112L NAND here, which means we’re looking at 4x 2 TB NAND chips, each with 16 1Tbit TLC dies on-board, twice as many dies as were used on the NAND chips for the 4 TB model.
The peak read speed of the new 8TB model is 7,200 MB/sec, which is actually a smidge below the performance the 4 TB and 2 TB models due to the overhead from the additional NAND dies. Meanwhile peak sequential write speeds remain at 6,600 MB/sec, while 4K random write performance maxes out at 1200K IOPS for both reads and writes. It goes without saying that this is a step below the performance of the market flagship PCIe 5.0 SSDs available today, but it’s going to be a bit longer until anyone else besides Phison is shipping a PCIe 5.0 controller – never mind the fact that these drives aren’t available in 8 TB capacities.
The 8 TB SN850X also keeps the same drive endurance progression as the rest of the SN850X family. In this case, double the NAND brings double the endurance of the 4 TB model, for an overall endurance of 4800 terabytes written (TBW). Or in terms of drive writes per day, this is the same 0.33 rating as the other SN850X drives.
| WD_Back SN850X SSD Specifications | ||||
| Capacity | 8 TB | 4 TB | 2 TB | 1 TB |
| Controller | WD In-House: 8 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 available both with and without aluminum heatsink. The version without a heatsink aimed at laptops and BYOC setups costs $849.99, whereas a version with an aluminum heat spreader comes at $899.99. In both cases the 8 TB drive carries a significant price premium over the existing 4 TB model, which is readily available for $259.99.
This kind of price premium is unfortunately typical for 8 TB drives, and will likely remain so until both supply and demand for the high-capacity drives picks up to bring prices down. Still, with rival drives such as Corsair’s MP600 Pro XT 8 TB and Sabrent’s Rocket 4 Plus 8 TB going for $965.99 and $1,199.90 respectively, the introduction of the 8 TB SN850X is definitely pushing high-capacity M.2 SSD prices down, albeit slowly. So for systems with multiple M.2 slots, at least, the sweet spot on drive pricing is still to get two 4 TB SSDs.
