Designed primarily for OEM integration into laptops and ultrabooks, the Samsung SM951 was Samsung’s first consumer-grade NVMe SSD, offering significant performance advantages over SATA-based storage solutions.
The SM951 was positioned as Samsung’s flagship M.2 SSD alongside the similar 950 PRO, which was available in retail. Its true successor was the Samsung 960 PRO.
Controller & NAND Type
Samsung’s SM951 utilizes Samsung’s proprietary UBX controller, a custom-designed 3-core ARM Cortex-R4 processor manufactured on a 40nm process. This controller was specifically optimized for NVMe command processing and featured Samsung’s advanced error correction algorithms. The UBX controller supported up to 8 NAND channels and incorporated Samsung’s TurboWrite technology for enhanced write performance.
The drive’s onboard LPDDR3 DRAM cache varies by capacity, with the 128 GB model offering 256 MB LPDDR3 and the larger 256/512 GB capacities coming with 512 MB of LPDDR3. The cache operates at 1600MHz and serves as both a write buffer and metadata storage, significantly improving random I/O performance and overall system responsiveness.
The SM951 employs Samsung MLC (Multi-Level Cell) NAND flash memory manufactured on a 16 nm process node.
Power Consumption
Power consumption is not stated officially but has been estimated to just over 8 Watts peak (active write mode). Idle: 50mW (typical), sleep (L1.2): 2mW.
The drive supports advanced power management states including APST (Autonomous Power State Transition) and ASPM (Active State Power Management), making it suitable for laptops and other portable devices.
Write Endurance and Over-Provisioning
Write endurance in terabytes written (TBW) is similarly not provided officially, but should be considerable due to the MLC NAND type. Additionally, the SM951 includes approximately 7% over-provisioning space reserved for wear leveling, bad block management, and maintaining consistent performance over the drive’s lifespan.
Encryption Capabilities
The SM951 supports TCG Opal 2.0 and IEEE-1667 encryption standards, providing hardware-based security features. The drive includes AES 256-bit encryption capabilities, though full BitLocker support was limited in early firmware versions. Enterprise security features include secure erase functionality for data sanitization.
Performance
The NVMe-equipped SM951 delivered exceptional performance for its era:
- Sequential Read: Up to 2,150 MB/s (512GB model)
- Sequential Write: Up to 1,550 MB/s (512GB model)
- Random Read: Up to 90K IOPS
- Random Write: Up to 70K IOPS
Performance scaling was evident across capacities, with larger models generally achieving higher throughput due to increased parallelism across more NAND channels.
Market Impact and Legacy
The SM951 played a crucial role in establishing NVMe as the new standard for high-performance storage. As one of the first consumer NVMe SSDs, it demonstrated the significant performance advantages possible with the NVMe protocol over traditional SATA interfaces. The drive’s success paved the way for Samsung’s subsequent 960 PRO and 970 PRO lineups, which became widely available in retail channels.
Specifications Compared to 950 PRO
| 950 PRO Specifications | 950 Pro 512GB | 950 Pro 256GB | SM951-NVMe 512GB (OEM) |
|---|---|---|---|
| Form Factor | M.2 2280 | M.2 2280 | M.2 2280 |
| Controller | UBX | UBX | UBX |
| Interface/ Protocol | PCIe 3.0 x4/ NVMe | PCIe 3.0 x4/ NVMe | PCIe 3.0 x4/ NVMe |
| DRAM | 512MB | 512MB | 512MB |
| NAND | 32-Layer MLC V-NAND | 32-Layer MLC V-NAND | 16nm 64Gbit MLC |
| Sequential Read | 2,500MB/s | 2,200MB/s | 2,150MB/s |
| Sequential Write | 1,500MB/s | 900MB/s | 1,550MB/s |
| 4KB Random Read (QD32) | 300K IOPS | 270K IOPS | 300K IOPS |
| 4KB Random Write (QD32) | 110K IOPS | 85K IOPS | 100K IOPS |
| Power | 7.0W (burst), 5.7W (average), 1.7W (idle) | 6.4W (burst), 5.1 (average), 1.7W (idle) | 8.9W |
| Encryption | AES-256, TCG Opal 2.0 | AES-256, TCG Opal 2.0 | AES-256, TCG Opal 2.0 |
| Endurance | 400 TBW | 200 TBW | N/A |
| Warranty | 5 Year | 5 Year | N/A |
| Launch Date | October 2015 | October 2015 | June 2015 |
Professional Reviews
The SM951 is easily the fastest consumer SSD we have ever tested and brings NVMe to the masses for the first time.
Samsung’s SM951 delivers on the promise of NVMe with blistering sequential performance that makes SATA SSDs look sluggish.
The Samsung SM951 NVMe looks promising, but it is complicated and it might be a good thing that it isn’t readily available on the market just yet.
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