SanDisk’s WD Black SN7100 is a midrange to high-end NVMe solid-state drive (SSD) manufactured by SanDisk (formerly part of Western Digital). It was released in November 2024 as a successor to the popular WD Black SN770 and is positioned as a power-efficient PCIe Gen4 drive for laptops, gaming PCs/handheld, and desktop systems.
The WD Black SN7100 competes in the high-performance yet affordable PCIe 4.0 segment and its main competitors at the time include the Samsung 990 EVO Plus, and Crucial P5 Plus / T500. The SN7100 stands out through industry-leading power efficiency, achieving up to 729 MB/s per watt during file transfers – a substantially higher figure than most competitors including the Samsung 990 EVO Plus (524 MB/s per watt) and the older WD Black SN850X (449 MB/s per watt).
Technical Specifications
| Specification | 500GB | 1TB | 2TB | 4TB |
|---|---|---|---|---|
| Model Number | WDS500G4X0E-00CJA0 | WDS100T4X0E-00CJA0 | WDS200T4X0E-00CJA0 | WDS400T4X0E-00CJA0 |
| Interface | PCIe Gen4 x4, NVMe 2.0 | PCIe Gen4 x4, NVMe 2.0 | PCIe Gen4 x4, NVMe 2.0 | PCIe Gen4 x4, NVMe 2.0 |
| Form Factor | M.2 2280 | M.2 2280 | M.2 2280 | M.2 2280 |
| Controller | SanDisk Polaris 3 (A101-000172-A1) (4-Channel) | SanDisk Polaris 3 (A101-000172-A1) (4-Channel) | SanDisk Polaris 3 (A101-000172-A1) (4-Channel) | SanDisk Polaris 3 (A101-000172-A1) (4-Channel) |
| NAND Type | Kioxia BiCS8 218-Layer TLC | Kioxia BiCS8 218-Layer TLC | Kioxia BiCS8 218-Layer TLC | Kioxia BiCS8 218-Layer TLC |
| DRAM Cache | None (64 MB HMB) | None (64 MB HMB) | None (64 MB HMB) | None (64 MB HMB) |
| Sequential Read (Max) | 6,800 MB/s | 7,250 MB/s | 7,250 MB/s | 7,000 MB/s |
| Sequential Write (Max) | 5,800 MB/s | 6,900 MB/s | 6,900 MB/s | 6,700 MB/s |
| Random Read IOPS (4K QD32) | 760K | 1,000K | 1,000K | 900K |
| Random Write IOPS (4K QD32) | 1,200K | 1,400K | 1,400K | 1,350K |
| Endurance (TBW) | 300 | 600 | 1,200 | 2,400 |
| SLC Cache Size | ~165GB | ~330GB | ~650-700GB | ~1.3TB |
| Power Consumption (Active) | 3.0W (Average) 4.1W (Peak) | 3.0W (Average) 4.1W (Peak) | 3.0W (Average) 4.1W (Peak) | 3.0W (Average) 4.1W (Peak) |
| Power Consumption (Idle) | 969mW (L1 ASPM enabled) | 969mW (L1 ASPM enabled) | 969mW (L1 ASPM enabled) | 969mW (L1 ASPM enabled) |
| Warranty | 5 Years | 5 Years | 5 Years | 5 Years |
Controller
The SN7100 uses the SanDisk Polaris 3 controller (model A101-000172-A1), a proprietary 4-channel DRAM-less design that relies on Host Memory Buffer (HMB) technology for mapping tables. This controller is an iterative improvement over previous Polaris silicon used in drives like the Blue SN580, with the primary enhancement being an increased bus rate capable of supporting 2,400 MT/s NAND interfaces. It is manufactured using 16 nm process technology and optimized specifically for SanDisk’s BiCS flash memory.
Cache: DRAM-less
Like the similar but QLC-based WD Blue SN5100, the WD Black SN7100 comes with a sophisticated pseudo-SLC (Single-Level Cell) caching system to accelerate write performance. It varies by capacity (estimates):
- 500GB model: Approximately 165GB SLC cache
- 1TB model: Approximately 330GB SLC cache
- 2TB model: Approximately 650-700GB SLC cache
- 4TB model: Estimated 1.3TB SLC cache (based on typical allocation)
A hybrid cache strategy combines both static and dynamic SLC allocation, allowing it to maintain high performance during extended write operations before transitioning to native TLC write speeds (of around 2.86 GB/s for the 2TB model).
Power Consumption
As mentioned previously, power efficiency is one of the key selling points for the SN7100:
- Idle Power: 969mW with L1 ASPM enabled (mobile configuration)
- Active Power (Average): 3.0W during sustained transfers
- Maximum Power: 4.10W under peak load
- Efficiency: Up to 100% more power efficient than the previous generation SN770 at maximum speed
This exceptional power efficiency makes the drive particularly suitable for battery-powered devices including laptops and gaming handhelds, where it can potentially extend battery life compared to competing solutions.
Reviews
The WD Black SN7100 2 TB SSD sets a new standard as the fastest Gen 4 SSD we’ve ever tested. It’s also priced well and highly energy-efficient, which helps keep temperatures down.
The new power efficiency champion is here. WD’s Black SN7100 NVMe SSD sets a new benchmark with its low power consumption, and its random read performance is also similarly surprising
The 2TB Black SN7100 proved the fastest PCIe 4.0 host memory buffer (HMB) design SSD we’ve put through the wringer so far… I’m calling the SN7100 top dog in the PCIe 4.0/HMB category
… Black SN7100 delivers some seriously impressive performance, particularly on the read front.
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