WD_BLACK SN850 1TB NVMe SSD: PCIe Gen4 speeds, specs and who it suits

The WD_BLACK SN850 is an internal NVMe solid state drive built for gaming PCs, in the compact M.2 2280 format. It uses a PCIe Gen4 connection to cut loading times and move large game files quickly. Here is what its numbers mean and what it needs from your computer.

What PCIe Gen4 and NVMe mean

NVMe is the protocol that lets a drive talk to the processor over PCIe lanes, instead of the older SATA connection used by 2.5-inch SSDs. SATA tops out at roughly 550 MB/s in practice. PCIe Gen4 doubles the per-lane bandwidth of Gen3, which is how a drive like this can be rated at several thousand megabytes per second.

The SN850 is described as "next-gen PCIe Gen4 technology". To reach its rated speeds, the motherboard slot needs to support Gen4. In an older Gen3 slot, drives of this type generally still work, but they are limited by the slot's bandwidth.

Reading the speed figures

WD_BLACK rates the 1TB model at up to 7,000 MB/s sequential reads and 5,300 MB/s sequential writes, with up to 1,000,000 IOPS (input/output operations per second) on the 1TB and 2TB models. Sequential speed matters when copying or loading big files, such as a game's asset packs. IOPS describes how many small reads and writes the drive handles each second, which affects how responsive the system feels when many small files are touched.

The brand notes that these figures come from internal testing and that performance varies with the host device, usage conditions and drive capacity. Real-world results depend on the rest of the system, and most programs never use a drive's full peak speed.

Capacity and how it is counted

The model here is 1TB; the range goes up to 2TB. The brand counts 1TB as one trillion bytes, and notes that actual user capacity may be less depending on the operating environment. That is normal for storage: operating systems usually report a slightly smaller figure because they count differently and reserve some space for the file system.

Form factor and installation

The drive is an M.2 2280 stick, about 80 mm long, and the listing gives its size as roughly 3.1 x 0.9 x 0.1 inches. It plugs straight into an M.2 slot on the motherboard, with no cables. Many motherboards and some consoles that accept M.2 drives have a heatsink cover over the slot, which helps keep fast drives cool under long transfers. Check your board's manual for which M.2 slots run at Gen4 speed, as some share bandwidth with other ports.

WD_BLACK Dashboard software

WD_BLACK offers downloadable Dashboard software for customizing and controlling the gaming experience. Software like this typically shows drive health and temperature, and may offer firmware updates and other settings. Check the brand's site for current features and supported operating systems.

Who it suits

The listing positions the SN850 for gaming desktops and similar systems that have a free Gen4 M.2 slot. It is stated as not intended for NAS or server environments, so it is not the right choice for a network storage box or a rack server.

What to check before you buy

• Slot type and speed: confirm you have a free M.2 slot that supports NVMe and PCIe Gen4.
• Length: M.2 2280 is the common size, but confirm your board supports it.
• Heatsink clearance: if your board has a cover over the slot, check the drive fits beneath it.
• Use case: the brand states it is not meant for NAS or server use.
• Capacity: think about your game library and file sizes, plus free space for updates.
• Backups: keep important files backed up, whatever drive you use.

The short version

• A 1TB PCIe Gen4 NVMe SSD in M.2 2280 format with 3D NAND.
• Rated at up to 7,000 MB/s reads, 5,300 MB/s writes and 1,000,000 IOPS.
• Needs a Gen4 M.2 slot to reach its rated speeds.
• WD_BLACK Dashboard software is available to download.
• Aimed at gaming PCs, and not intended for NAS or server use.

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