Packaging

The Drive

The drive uses the M.2 2280 form factor, which makes it 22 mm wide and 80 mm long.


While most other M.2 NVMe SSDs transfer data over the PCI-Express 3.0 x4 interface, the WD Black SN850 connects to the host system over a PCI-Express 4.0 x4 interface, which doubles the theoretical bandwidth.


On the PCB, you'll find the controller, two flash chips, and one DRAM chip; the other side of the PCB is empty.

Chip Component Analysis

This is SanDisk's new PCIe Gen 4 controller. WD gave it the marketing name "WD G2." The controller uses eight flash channels and has support for NVMe 1.4, TLC, and DDR4 DRAM.


The two flash chips are Toshiba 96-layer 3D TLC NAND. Each chip has a capacity of 512 GB.


A Nanya DDR4-2666 chip provides 1 GB of fast DRAM storage for the controller to store the mapping tables.