Silicon Motion Showcases Energy-Efficient PCIe 5.0 SSD Controller: SM2508

Wrapping up our coverage on SSD controllers at Computex 2024, we now shift focus to the last major player showcased: Silicon Motion. Despite being tardy to the PCIe Gen5 SSD scene (unlike its competitor Phison, which has had its high-end PS5026-E26 controller available for nearly 18 months), Silicon Motion is gearing up for the PCIe 5.0 era with a standout offering: the SM2508 controller. This high-end controller is designed to be energy-efficient, catering to low-power drives.

The SM2508 is a PCIe Gen5 x4 controller that features a remarkably low active power consumption of 3.5W. When integrated into an M.2 SSD, this efficiency enables manufacturers to produce drives that operate at 7 Watts or lower, according to Silicon Motion. Fabricated using TSMC’s N6 process technology—a 7nm-class node with an optical shrink—the SM2508 is set to be one of the most advanced controllers upon release. This manufacturing sophistication allows for a higher density of cores and features while maintaining controlled power consumption and compact chip size.

Silicon Motion NVMe Client SSD Controller Comparison
  SM2508 SM2264 SM2268XT2 SM2269XT
Market Segment High-End Mainstream
Manufacturing Process 6nm 12nm 12nm 12nm
CPU Cores 4x Cortex R8 4x Cortex R8 2x Cortex R8 2x Cortex R8
Error Correction 4K+ LDPC 4K LDPC 4K+ LDPC 4K LDPC
Host Interface PCIe 5.0 x4 PCIe 4.0 x4 PCIe 4.0 x4 PCIe 4.0 x4
NVMe Version NVMe 2.0 NVMe 1.4 NVMe 2.0 NVMe 1.4
NAND Channels, Interface Speed 8 ch,
3600 MT/s
8 ch,
1600 MT/s
4 ch,
3600 MT/s
4 ch,
1600 MT/s
Sequential Read 14.5 GB/s 7.5 GB/s 7.4 GB/s 5.1 GB/s
Sequential Write 14 GB/s 7 GB/s 6.7 GB/s 4.8 GB/s
4KB Random Read IOPS 2500k 1300k 1200k 900k
4KB Random Write IOPS 2500k 1200k 1200k 900k

The SM2508 SSD controller’s front-end architecture is built around four Arm Cortex-R8 cores, making it a robust controller (for comparison, Phison’s E26 uses two Arm Cortex R5 cores with an accelerator). This controller is designed for DRAM integration, supporting both DDR4 and LPDDR4.

The chip’s back-end features eight NAND channels with 32 CE targets, supporting interface speeds up to 3600 MT/s. Overall, Silicon Motion claims the controller can achieve sequential read speeds of up to 14.5GB/sec and write speeds of up to 14 GB/s, with 4K random read and write performances reaching up to 2.5 million IOPS. Notably, an SM2508-equipped demo drive at Computex exceeded expectations, recording a 14.9GB/sec read speed in CrystalDiskMark.

Silicon Motion and its partners are currently finalizing the SM2508’s firmware and qualifying it with various manufacturers’ TLC NAND. The controller also supports QLC NAND, although it’s unlikely that such a powerful controller would be paired with slower NAND any time soon.

At Computex, Silicon Motion showcased a live demo of an SM2508 drive. Various manufacturers also displayed SM2508-based drives, although these were static samples only.

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