WD_BLACK 4TB SN850X NVMe

WD_BLACK 4TB SN850X NVMe Review & Specifications

The WD_BLACK 4TB SN850X NVMe by WD is a NVMe solid-state drive (SSD) featuring 4000 GB of storage. It is built with TLC 112-layer NAND flash memory and utilizes a WD Black G2 (20-82-20035-B2) controller to manage data access, wear leveling, and overall performance. This drive runs on the PCIe 4.0 x4 interface (up to 16 GB/s) and utilizes the NVMe 1.4 protocol. NVMe 1.4 brought significant updates such as improved power management, persistent memory region support, and native command retry. The SSD comes in a M.2 2280 form factor. PCIe 4.0 is backward compatible with older PCIe slots, but speeds will adjust accordingly.

NVMe SSD Performance

Sequential read and write speeds reach 7300 MB/s and 6600 MB/s respectively, while random read/write performance delivers up to 1200k and 1000k IOPS. The drive offers an endurance rating of 2400 TBW and is backed by a 5-year manufacturer warranty.

This SSD includes a dedicated 2048 MB DRAM cache module running at 3200 MHz. This discrete DRAM chip serves as a high-speed buffer between the controller and NAND flash, significantly reducing latency and improving random read/write performance. DRAM allows the controller to store the Flash Translation Layer (FTL), which is essential for efficient address mapping and wear leveling. Combined with a 1152 GB Dynamic + 48 GB Static SLC write cache, it offers excellent burst speeds and consistent performance under heavy workloads.

This SSD module provides strong mid-range performance, achieving 73.7% of the highest score in our benchmark. It delivers excellent responsiveness and load times for a wide variety of tasks, making it ideal for mainstream gaming setups, content creation, software development, and multitasking-oriented workflows. Unless you're working with large-scale real-time data or intensive write-heavy workloads, this level of performance is more than sufficient for demanding users.

Cost-Effectiveness

From a cost-per-storage perspective, this SSD provides moderate value at $71.0 per terabyte. The overall combined performance-to-price ratio, which evaluates both maximum performance and total storage capacity per dollar, is calculated at 72.6%. Based on this metric, the drive is a solid mid-range option that balances speed, capacity, and cost-effectiveness.