Western Digital has quietly introduced an 8TB version of its top-of-the-line SN850X SSD, doubling the maximum capacity of the popular drive family. The new drive offers comparable performance to the other members of the lineup, but with twice the capacity of the previous top-of-the-line model, and a higher price tag than the previous one.
Western Digital introduced its WD_Black SN850X SSDs in the summer of 2022, releasing 1TB and 2TB single-sided models, as well as a 4TB double-sided model. But now, nearly two years later, the company has seen fit to release the even higher capacity 8TB model to serve as its flagship PCIe 4.0 SSD, and to keep up with the times of NAND pricing and SSD capacity demands.
Like the other SN850X models, WD is using its own 8-channel controller for the new 8TB model, which features a PCIe 4.0 x4 interface. And since 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 side, WD is apparently still using its BiCS 5 112L NAND here, which means we’re looking at four 2TB NAND chips, each with 16 1Tbit TLC dies embedded in it, which is twice as many dies as are used on the 4TB model’s NAND chips.
The new 8TB model has a maximum read speed of 7,200MB/s, which is actually slightly lower than the 4TB and 2TB models due to the overhead of the additional NAND dies. Meanwhile, maximum sequential write speeds remain at 6,600MB/s, while 4K random write performance tops out at 1,200,000 IOPS for both reads and writes. Needless to say, this is a notch below the performance of the flagship PCIe 5.0 SSDs available today, but it will be a while before anyone other than Phison ships a PCIe 5.0 controller – not to mention that these drives aren’t available in 8TB capacities.
The 8TB SN850X also maintains the same endurance progression as the rest of the SN850X family. In this case, double the NAND brings double the endurance of the 4TB model, for an overall endurance of 4,800 terabytes written (TBW). Or in terms of disk writes per day, that’s the same 0.33 rating as the other SN850X drives.
| WD_Back SN850X SSD Specifications | ||||
| Ability | 8 TB | 4 TB | 2 TB | 1 TB |
| Controller | WD internal: 8 channels, DRAM (DDR4) | |||
| NAND Flash Memory | WD BiCS 5 TLC | |||
| Form factor, interface | M.2-2280 double sided PCIe 4.0 x4, NVMe | M.2-2280 single sided PCIe 4.0 x4, NVMe | ||
| Sequential reading | 7200 MB/s | 7300 MB/s | 7300 MB/s | 7300 MB/s |
| Sequential writing | 6600 MB/s | 6600 MB/s | 6600 MB/s | 6300 MB/s |
| Random Read IOPS | 1200K | 1200K | 1200K | 800 000 |
| Random Write IOPS | 1200K | 1100K | 1100K | 1100K |
| SLC Caching | Yes | |||
| Opal TCG Encryption | 2.01 | |||
| guarantee | 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 (without heat sink) | $850 | $260 | $140 | $85 |
Western Digital’s WD_Black SN850X is available with and without an aluminum heatsink. The version without a heatsink for laptops and BYOC setups costs $849.99while a version with an aluminum heat sink is offered at $899.99In both cases, the 8TB hard drive comes at a significantly higher price than the existing 4TB model, which is readily available for $259.99.
This type of cost premium is unfortunately typical of 8TB drives and will likely remain so until supply and demand for high-capacity drives increases to drive prices down. Yet with competing drives like Corsair’s 8TB MP600 Pro XT and Sabrent’s 8TB Rocket 4 Plus, $965.99 And $1,199.90 The introduction of the 8TB SN850X is bringing down the prices of high-capacity M.2 SSDs, albeit slowly. So for systems with multiple M.2 slots, at least, the sweet spot for drives is still buying two 4TB SSDs.