WD_BLACK SN770
PCle Gen4 Interface | DRAM-Less Architecture with HMB | DirectStorage Optimization
Introduction
The WD_BLACK SN770 NVMe SSD represents a strategic evolution in consumer-grade PCIe 4.0 storage, blending affordability with performance previously reserved for premium drives. Positioned as a mid-tier solution, it challenges industry assumptions about DRAM-less architectures while appealing to gamers, content creators, and PC enthusiasts seeking cost-effective Gen4 speeds. Its release signals a broader market shift toward accessible high-speed storage without compromising reliability.
Product Overview
Designed for M.2 2280 slots, the SN770 employs Western Digital’s proprietary controller and 112-layer BiCS5 TLC NAND. Targeted at users upgrading from SATA SSDs or older PCIe 3.0 drives, it balances sequential throughput with energy efficiency. The drive operates without onboard DRAM, instead leveraging Host Memory Buffer (HMB) technology to utilize system RAM for caching. This design choice reduces manufacturing costs while maintaining competitive performance metrics.
Key Features
PCIe Gen4 Interface
The SN770 delivers sequential read speeds up to 5,150 MB/s and writes up to 4,900 MB/s in its 1TB/2TB configurations. This Gen4 implementation achieves 40-60% improvements over its predecessor while maintaining backward compatibility with PCIe 3.0 systems.
DRAM-Less Architecture with HMB
By eliminating onboard DRAM and utilizing HMB, the drive reduces power consumption by 20% compared to previous generations. This approach allows sustained performance for gaming and productivity workloads while extending laptop battery life.
DirectStorage Optimization
Prepared for next-gen gaming APIs, the SN770 supports Microsoft’s DirectStorage technology to accelerate asset loading in games designed for Windows 11/12. This future-proofing ensures compatibility with upcoming titles leveraging GPU decompression.
Performance Analysis
Sequential Speeds
In synthetic benchmarks, the drive consistently achieves 5,100-5,150 MB/s reads and 4,850-4,900 MB/s writes when operating within its SLC cache boundaries. Real-world file transfers show 3.8-4.2 GB/s sustained performance for large multimedia files.
Random Performance
With random 4K read/write IOPS reaching 740,000/800,000 respectively, the SN770 outperforms many DRAM-equipped competitors. This capability stems from advanced firmware optimization and the BiCS5 NAND’s four-plane architecture.
Thermal Management
A dynamic thermal throttling mechanism maintains surface temperatures below 70°C under sustained loads. The absence of a heatsink allows compatibility with laptop M.2 slots while preventing thermal-induced performance drops during typical gaming sessions.
Compatibility
Steam Deck and Handheld PCs
While the standard 2280-form SN770 doesn’t fit internally in devices requiring 2230 modules, users successfully deploy it via USB-C enclosures. External configurations achieve 900-1,100 MB/s speeds, suitable for game libraries and media storage.
Desktops and Laptops
Universal compatibility across Windows/Linux systems with PCIe 4.0/3.0 x4 M.2 slots. The drive’s 5.1W active power draw makes it particularly suitable for thin-and-light laptops seeking Gen4 performance without excessive battery drain.
Advantages and Limitations
Strengths
Price-to-Performance Ratio: Outperforms many DRAM-equipped Gen4 drives at 20-30% lower cost
Energy Efficiency: Ideal for mobile workstations requiring fast storage without compromising battery life
Constraints
HMB Dependency: Performance degrades in systems without NVMe 1.2+ support
Sustained Write Limitations: Heavy workloads exceeding SLC cache (150-300GB depending on capacity) trigger write speed reductions to 400-600 MB/s
Conclusion
The WD_BLACK SN770 redefines expectations for budget-oriented PCIe 4.0 SSDs, offering near-flagship performance in a power-efficient package. While not suitable for PlayStation 5 expansions or Raspberry Pi boot drives, it excels as a primary storage solution for gaming PCs and content creation laptops. Users prioritizing cost-effective Gen4 speeds over extreme endurance will find exceptional value, particularly in 1TB and 2TB configurations.
Works Cited
“WD Black SN770 NVMe SSD Review.” StorageReview, www.storagereview.com/review/wd-black-sn770-ssd-review.
“Western Digital Introduces WD_BLACK SN770.” AnandTech, www.anandtech.com/show/17238/western-digital-introduces-wd_black-sn770.
“WD Black SN770 SSD Review: Fast, Affordable, and Unusual.” PCWorld, www.pcworld.com/article/608860/wd-black-sn770-nvme-ssd-review.html.
