Silicon Power 4TB UD90 NVMe 4.0 Gen4 PCIe M.2 SSD

Silicon Power 4TB UD90 NVMe 4.0 Gen4 PCIe M.2 SSD Review & Specifications

The Silicon Power 4TB UD90 NVMe 4.0 Gen4 PCIe M.2 SSD by SP Silicon Power is a NVMe solid-state drive (SSD) featuring 4000 GB of storage. It is built with TLC 176-Layer NAND flash memory and utilizes a Phison E21T 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 5000 MB/s and 4500 MB/s respectively, while random read/write performance delivers up to 570k and 600k IOPS. The drive offers an endurance rating of 2400 TBW and is backed by a 5-year manufacturer warranty.

This SSD does not include a dedicated external DRAM cache chip. Instead, it relies on a small internal SRAM cache integrated into the controller, typically around 32 MB to 128 MB. Manufacturers may sometimes refer to this SRAM as "DRAM cache," but it is not the same as a discrete DRAM module. Furthermore, because it uses the NVMe interface, the SSD may also support Host Memory Buffer (HMB) — a feature that allocates a small portion of your system’s RAM (usually 64–128 MB) to act as a substitute for DRAM. While this design is cost-effective and suitable for everyday tasks, performance under heavy or sustained random I/O can be lower compared to full-DRAM SSDs. A Dynamic SLC cache is still included to help with write bursts and improve responsiveness.

This SSD module offers entry-level performance in our synthetic benchmark, scoring 63.7% relative to the fastest NVMe SSDs in our database. However, this classification doesn't always reflect real-world capability. Many drives in this range — especially those with DRAM cache, and even some newer, efficient DRAM-less models — can still deliver responsive performance in general computing, gaming, light creative work, and casual development environments. Unless your workload involves large file transfers or sustained heavy I/O, this level of performance is more than adequate.

Cost-Effectiveness

From a cost-per-storage perspective, this SSD offers below-average value at $120.0 per terabyte. The overall combined performance-to-price ratio, which evaluates both maximum performance and total storage capacity per dollar, is calculated at 79.7%. Based on this metric, the drive is a solid mid-range option that balances speed, capacity, and cost-effectiveness.