Introduction

If you've been following the SSD space at least a little bit, you definitely know Phison. Phison is the world's leading NAND flash controller manufacturer, recognized for its cutting-edge solutions that drive the performance of solid-state drives in millions of systems. Based in Taiwan, Phison has been at the forefront of storage technology, providing high-quality controllers for almost all SSD vendors, except for those that have their own controllers, like Samsung, WD and Hynix.



We are excited to present an early look at the Phison E31, an engineering sample of their newest controller, which is set to power a wide range of upcoming SSDs from various vendors. As the second PCIe 5.0 controller introduced, the E31 is specifically designed for cost-efficient solutions, while the flagship E26 continues to cater to high-performance needs. Gen 5 SSDs have been on the market for a bit over a year, and virtually all drives came with a Phison controller—the E26. The problem—they are expensive and consume a lot of power, which means large heatsinks—many with an active cooling fan—have to be used.

The E31 is designed to address that. It uses the 7 nm TSMC process, with a design focus on optimizing power. The controller is paired with Kioxia BiCS8 3D TLC NAND operating at 3600 MT/s. For cost reasons a DRAM cache chip is not included, but the controller will use up to 64 MB of main memory through the Host-Memory-Buffer (HMB) feature.

Phison E31 drives will be available in capacities of 1000 GB, 1024 GB, 2000 GB and 2048 GB. The endurance for this controller and flash combo is 1200 TBW, with 600 TBW expected for 1 TB models.

The Drive

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


PCI-Express 5.0 x4 is used as the host interface to the rest of the system, which doubles the theoretical bandwidth compared to PCIe 4.0 x4.


On the PCB you'll find the controller and two flash chips, a DRAM cache chip is not included.

Chip Component Analysis

The Phison E31 is the company's second PCI-Express 5.0 controller. It supports a four-lane configuration and four flash channels, it's a cost-optimized DRAM-less design. The controller is produced using a 7 nm process at TSMC Taiwan.


The two flash chips are Toshiba 218-layer 3D TLC NAND. Each chip has a capacity of 1 TB.

Test Setup

Synthetic Testing

• Tests are run with a 20-second-long warm-up time (result recording starts at second 21).
• Between each test, the drive is left idle for 60 seconds, to allow it to flush and reorganize its internal data.
• All write requests contain random, incompressible data.
• Disk cache is flushed between all tests.
• During these tests, M.2 drives are tested with additional active fan-cooling, to ensure thermal throttling can't happen

Real-life Testing

• After initial configuration and installation, a disk image is created; it is used to test every drive.
• Automated updates are disabled for the OS and all programs. This ensures that—for every review—each drive uses the same settings, without interference from previous testing.
• Our disk image consumes around 700 GB—partitions are resized to fill all available space on the drive.
• All drives are filled with random data to 85% of their capacity. This is intentional, to run the drive in realistic operating conditions—nobody uses a nearly-empty SSD in their system. It also puts additional stress on the pseudo-SLC cache subsystem, because there is less free NAND space to work with.
• Partitions are aligned properly.
• Disk cache is flushed between all tests.
• In order to minimize random variation, each real-life performance test is run several times, with reboots between tests to minimize the impact of disk cache.
• All application benchmarks run the actual application and do not replay any disk traces.
• Our real-life testing data includes performance numbers for a typical high-performance HDD, using results from a Western Digital WD Black 1 TB 7200 RPM 3.5" SATA. HDDs are significantly slower than SSDs, which is why we're not putting the result in the chart, as that would break the scaling, making the SSDs indistinguishable in comparison. Instead, we've added the HDD performance numbers in the title of each test entry.
• During these tests, M.2 drives are tested with additional active fan-cooling, to ensure thermal throttling can't happen