Western Digital WD_BLACK SN770 1000GB

SSD Description

The Western Digital WD_BLACK SN770 utilizes a vertically integrated architecture, featuring an in-house SanDisk 20-82-10081-A1 controller paired with Kioxia/SanDisk BiCS5 112-layer TLC NAND. This drive eschews onboard DRAM in favor of a Host Memory Buffer (HMB) configuration that uses a portion of system RAM for address mapping. The proprietary controller is engineered to saturate a significant portion of the PCIe 4.0 x4 bandwidth. The controller is power-efficient with lower thermal output compared to early-generation PCIe 4.0 controllers, and the drive uses a dynamic pseudo-SLC caching algorithm (nCache 4.0) that provides high burst speeds but will drop to native TLC speeds for sustained writes beyond the cache. Community findings indicate the HMB implementation can rival DRAM-equipped SSDs for random reads important to OS responsiveness and game load times, though latency can increase under heavy simultaneous read/write loads.

Key Specifications

• Interface: PCIe 4.0 x4, NVMe 1.4
• Sequential Read: 5,150 MB/s
• Sequential Write: 4,900 MB/s
• Controller: SanDisk 20-82-10081-A1 (Proprietary)
• NAND Flash: Kioxia/SanDisk BiCS5 112-Layer TLC
• DRAM Cache: None (HMB architecture)
• Physical Layout: Single-sided PCB (M.2 2280)
• Encryption: No hardware-based AES encryption support

Hardware Alternatives

• Lexar NM790 1000GB: Utilizes the Maxio MAP1602 controller and is a direct architectural competitor in the high-performance, DRAM-less Gen4 category, often trading blows with the SN770 in efficiency and burst speeds.
• Samsung 980 1000GB: Locked to PCIe 3.0 but shares the in-house controller plus HMB design philosophy, acting as a predecessor to this architectural approach in the mainstream market.
• Crucial P5 Plus: Uses a Micron controller with onboard DRAM and is cited as a direct competitor in performance metrics; consumer trace testing shows the SN770 often matches its load times.