Today we are looking at WD’s relatively new SN850X. This Black-line drive is the successor to WD’s Black SN850 which we have previously covered. The original WD Black SN850 was part of the second wave of PCIe Gen 4 drives, and as such was one of the first drives to really push the limits of what a PCIe 4.0 x4 interface can handle. The SN850X is here to follow up, offering relatively similar specs but with an updated set of internal components. Also, for brevity, I will be referring to this drive as simply the SN850X rather than the WD Black SN850X for most of this review, just because that is a bit long-winded.
WD Black SN850X 1TB NVMe SSD
The WD SN850X 1TB comes in a single-sided M.2 2280 (80mm) form factor and is available both with and without a heatsink. My review model is the bare drive.
Similar to the original SN850, the new X model is fairly vertically integrated. By that, I mean that the controller is a custom SanDisk design, SanDisk being wholly owned by WD. In addition, the NAND on the SN850X is BiCS5 112-layer TLC, and BiCS5 was co-developed by WD and Kioxia. The controller used on the SN850X would appear to be an updated version of the one used on the SN850, with the SN850X model marked as B2 and the original SN850 marked as A1. 112-layer TLC is also an upgrade, as the original SN850 used 96-layer NAND. Rounding out the drive components is a DDR4 DRAM cache.
As mentioned, my review model of the SN850X does not include a heatsink but the design of the heatsink model seems nearly identical to the original SN850, and I believe my criticisms of that heatsink will be applicable here. To reiterate from my original review, potential buyers need to be aware this heatsink is not intended to be removable. Removing the heatsink will damage either the heatsink, the SSD, or both. When I removed the original SN850 from its heatsink, the heatsink could never be used again because the metal clips were permanently bent. The inability to remove the heatsink might affect some users with motherboards that have built-in M.2 heatsinks, and if that is the case, then buyers need to take care to acquire the SN850X that comes without the heatsink. Once again, I hope that in the future, WD can settle on a heatsink design that is removable in a non-destructive manner similar to the recently reviewed Lexar NM800 Pro.
WD SN850X 1TB BackThe back of the SSD is essentially blank.
WD SN850X SSD Specs
The SN850X line of SSDs is available in sizes between 1 TB and 4 TB.
This is the first time that reviewing a 1TB model drive means I am looking at the baby of the SKU list. In the future, STH will be standardizing on 2TB SSDs; that move will come with the new PCIe Gen5 compatible test platform. Stay tuned for news on that in the future!
For now, looking at the 1TB model drive we have rated sequential read speed of 7300 MB/s and sequential write of 6300 MB/s. Both of these represent moderate improvements over the original SN850 1TB model, which was rated for 7000 MB/s and 5300 MB/s, respectively.
The endurance and warranty, on the other hand, have stayed consistent with the first gen SN850 drive. 600 TBW is exactly the amount I consider acceptable for a premium drive, though many high-quality drives now exceed that amount. A 5-year warranty is also the industry standard for drives of this caliber, so it is good to see that here.
CrystalDiskInfo can give us some basic information about the SSD and confirms we are operating at PCIe 4.0 x4 speeds using NVMe 1.4.
Test System Configuration
We are using the following configuration for this test:
- Motherboard: ASUS PRIME X570-P
- CPU: AMD Ryzen 9 5900X (12C/24T)
- RAM: 2x 16GB DDR4-3200 UDIMMs
Our testing uses the WD SN850X 1TB as the boot drive for the system, installed in the M.2_1 slot on the motherboard. The drive is filled to 85% capacity with data and then some is deleted, leaving around 60% used space on the volume.
Next, we are going to get into our performance testing.