Western Digital’s SN850X and SN7100 are both high-performance Gen4 NVMe SSDs capable of over 7 GB/s read speeds. At first glance, it’s surprising that the older SN850X often costs more than the newer SN7100. Here’s why and how they stack up side-by-side.
1. DRAM vs DRAM-less Design
- SN850X includes dedicated DRAM memory, which stores the SSD’s “map” (Flash Translation Layer) for faster access under heavy workloads.
- SN7100 is DRAM-less, using Host Memory Buffer (HMB) technology that borrows a small portion of your system’s RAM instead. This makes it cheaper, cooler, and more power-efficient, but less consistent in heavy sustained writes.
2. Target Market & Branding
- SN850X was launched in 2022 as WD’s flagship gaming and enthusiast SSD with a premium price tag.
- SN7100, released in 2024, focuses on value and efficiency, keeping speeds high for everyday use and gaming without the higher production cost.
3. Side-by-Side Specs & Performance
| Feature | WD Black SN850X | WD Black SN7100 |
|---|---|---|
| Release Year | 2022 | 2024 |
| NAND Type | 112-layer TLC (older gen) | 218-layer BiCS8 TLC (newer gen) |
| Controller | WD custom G2 | WD custom (newer, DRAM-less) |
| DRAM Cache | Yes (DDR4) | No (uses HMB) |
| Form Factor | Double-sided | Single-sided |
| Sequential Read | Up to 7,300 MB/s | Up to 7,250 MB/s |
| Sequential Write | ~6,300–6,600 MB/s | ~6,700–6,900 MB/s |
| Random 4K | Excellent | Best-in-class (slightly better in gaming loads) |
| Sustained Writes | Strong, holds high speeds longer | Slows sooner when cache is full |
| Power Use (max) | ~7.4 W | ~4.5 W |
| Idle Power | ~1.1 W | ~0.095 W |
| Best Use Case | Heavy sustained workloads, content creation | Gaming, laptops, consoles, everyday use |
| Typical Price | Higher | Lower |
4. Price Legacy
Even though the SN7100 is newer, the SN850X:
- Uses more expensive components (DRAM).
- Launched as a high-end flagship with a higher MSRP.
- Still appeals to professionals and enthusiasts who need long, sustained write performance.
Which One Should You Choose?
| Your Use Case | Recommended Drive | Why |
|---|---|---|
| Gaming / Everyday Desktop Use | SN7100 | Cooler, more efficient, slightly better in game load speeds |
| Laptops & Consoles (PS5/Xbox) | SN7100 | Single-sided, low power, runs cooler |
| Heavy Sustained Workloads (Editing, 3D) | SN850X | DRAM keeps speeds high for long writes |
| Mixed Professional + Gaming Use | SN850X | Balance of top-tier sustained and random performance |
Bottom line:
If your priority is gaming, PS5 upgrades, or everyday PC use, go with the SN7100, it’s newer, cooler, and costs less. If you work with large files daily and need consistent top speeds for minutes or hours at a time, the SN850X still earns its higher price.