Western Digital WD_BLACK SN770 250GB

SSD Description

The Western Digital WD_BLACK SN770 250GB uses a vertically integrated, proprietary architecture built around Western Digital’s in-house DRAM-less controller paired with BiCS5 112-layer 3D TLC NAND. To compensate for the lack of onboard DRAM, the drive implements Host Memory Buffer (HMB) so the controller can use a portion of system RAM for the translation layer table. As the lowest-capacity 250GB variant, it is physically limited by the number of NAND dies available for interleaving, which restricts its write saturation potential compared to the 1TB and 2TB models. The controller prioritizes power efficiency, producing a thermal profile that rarely requires a dedicated heatsink; the dynamic SLC cache is relatively small, and once it is exhausted during sustained transfers, write speeds drop to native TLC levels. Users can enable "Game Mode" in WD Dashboard to prevent the drive from entering low-power states and maintain consistent latency.

Key Specifications

• Capacity: 250GB
• Interface: PCIe 4.0 x4 (NVMe 1.4)
• Sequential Read: 4,000 MB/s
• Sequential Write: 2,000 MB/s
• Controller: SanDisk/WD Proprietary (20-82-10081-A1)
• NAND Flash: Kioxia/WD BiCS5 112-Layer TLC
• DRAM Cache: None (HMB Support)
• Endurance: 200 TBW
• Form Factor: Single-sided M.2 2280

Hardware Alternatives

• WD Blue SN580: Shares a very similar architectural foundation (controller logic and BiCS5 NAND) but operates with more conservative firmware tuning and lower peak bandwidth caps.
• WD_BLACK SN850X: Represents the upper tier of this lineage; while it uses BiCS NAND, it utilizes a more robust controller with dedicated DRAM and PCIe 4.0 saturation speeds.
• Samsung 980 250GB: A direct conceptual rival as a DRAM-less proprietary drive, though the 980 is limited to the PCIe 3.0 interface.
• Lexar NM710: Uses a Maxio MAP1602 controller; competes in the same DRAM-less PCIe 4.0 mid-range tier, offering similar sequential throughput targets.