Kingston A400 480GB

The Kingston A400 480GB is a DRAM-less SATA III drive using a 2-channel controller design and a variable internal BOM. Units commonly ship with either the Phison S11 (PS3111-S11) or Silicon Motion SM2258XT/SM2259XT controllers and various iterations of 3D NAND (TLC or QLC). The drive relies on a static pseudo-SLC cache to reach its rated sequential bursts before falling back to lower native NAND speeds. Field reports note significant variance in sustained write performance by NAND/controller revision and a reported "SATAFIRM S11" firmware panic affecting some Phison S11 units that can render data inaccessible. As a DRAM-less SATA device without HMB, random 4K latency increases noticeably during mixed workloads compared to DRAM-equipped SATA alternatives.

Key Specifications

• Interface: SATA Rev. 3.0 (6Gb/s)
• Sequential Read/Write: 500 MB/s / 450 MB/s
• Controller: Variable (Phison S11, SMI SM2258XT, or SM2259XT)
• Controller architecture: 2-channel DRAM-less design
• NAND Flash: 3D NAND (Variable TLC or QLC)
• DRAM Cache: None (DRAM-less)
• Caching: Static pseudo-SLC cache
• Endurance: 160 TBW (Total Bytes Written)
• Chassis: Plastic/Metal Hybrid 2.5" 7mm Case

Hardware Alternatives

• PNY CS900: Often serves as a hardware clone to the Phison-based versions of the A400, frequently utilizing the same Phison S11 controller and similar NAND configurations, resulting in nearly identical synthetic performance profiles.
• Crucial BX500 480GB: A direct architectural competitor that, like the A400, uses a DRAM-less Silicon Motion (SM2258XT/SM2259XT) controller design and faces similar thermal and sustained write limitations.
• SanDisk SSD PLUS 480GB: Targets the same entry-level tier; modern iterations use DRAM-less controllers (often proprietary or rebranded SMI) with performance characteristics comparable to the A400's QLC variants.