Western Digital WD SN5100 4TB Review — QLC Bulk Storage, Gen4 Speed (2026)
Quick answer
The Western Digital WD SN5100 4TB is the bulk-storage play in the fastest QLC platform TechPowerUp has ever tested: 6,900/6,700 MB/s ratings, 1,200 TBW of endurance and five years of warranty across four terabytes of single-sided QLC.
Read: 6900 MB/s Write: 6700 MB/s Endurance: 1200 TBW Warranty: 5 years Interface: M.2 4.0 x 4
The Western Digital WD SN5100 4TB turns QLC into credible bulk storage — 6,900 MB/s Gen4 reads, 1,200 TBW of endurance and a 5-year warranty on a single-sided board.
Controller & Memory
The Western Digital WD SN5100 4TB is the capacity that justifies the family's existence: four terabytes of QLC flash behaving, in burst work, like a drive a class above its NAND. The platform is a single-sided M.2 2280 board on PCIe 4.0 x4 and NVMe 2.0 — SanDisk's Polaris 3 controller, 218-layer BiCS8 3D QLC NAND in CMOS-bonded-array form, up to 64 MB of Host Memory Buffer instead of DRAM, and SanDisk's nCache 4.0 pseudo-SLC write cache smoothing bursts. With Western Digital and SanDisk now one brand, identical hardware sells under either name; TechPowerUp's review of the 2 TB sibling called the platform the fastest QLC design the site has tested, and PCMag's 4 TB review found strong performance across most of its benchmarks.
At 4 TB the ratings shift slightly from the smaller capacities: 6,900 MB/s sequential reads rather than 7,100, with writes holding at 6,700 MB/s and random figures of 900K reads and 1,100K writes. Endurance is rated at 1,200 TBW under a 5-year warranty — the family maximum, double the 2 TB model's 900 TBW, though the per-terabyte allowance halves to 300 TBW. QLC density is what makes a drive this large possible in this tier. Platform-level testing explains the burst behavior: Tom's Hardware's saturation run on the 2 TB model held roughly 6.45 GB/s for over a minute on a pseudo-SLC cache exceeding 500 GB, while post-cache writing settles to a few hundred megabytes per TechPowerUp's measurements.
The audience is the archive builder: a Steam library that has outgrown 2 TB, a video project bin, a console expansion at a serious size. Sony's PS5 criteria — PCIe 4.0, 5,500 MB/s-plus reads, M.2 2280 with heatsink — are met on paper, with a heatsink added. Crucial's P3 Plus offers similar QLC positioning at lower speed, while the WD Black SN850X 4 TB serves buyers who need DRAM-cached sustained performance.
Storage Comparisons:
WD SN5100 Performance & Benchmarks
Western Digital rates the 4 TB SN5100 at 6,900 MB/s sequential reads, 6,700 MB/s writes, 900K random reads and 1,100K random writes — the read figure a touch below the 7,100 MB/s of the 500 GB through 2 TB models, writes unchanged. Platform-level testing supports the family's credibility: StorageReview measured 7,329/6,740 MB/s on the 2 TB model, TechPowerUp judged the family the fastest QLC design it has benchmarked, and PCMag's assessment of the 4 TB drive found strong performance across most of its benchmarks for a DRAM-less QLC product.
Western Digital WD SN5100 4 TB vs M.2 4.0 x 4 peers
Switch between sequential throughput and random IOPS to see how this drive stacks up against other M.2 4.0 x 4 SSDs in our database. The highlighted bar is the drive on this page — click any other bar to open that drive.
- Patriot Viper PV593 1 TB: 14,500 MB/s read, 14,000 MB/s write
- Patriot Viper PV593 2 TB: 14,500 MB/s read, 14,000 MB/s write
- Patriot Viper PV593 4 TB: 14,500 MB/s read, 14,000 MB/s write
- Patriot Viper PV573 2 TB: 14,000 MB/s read, 12,000 MB/s write
- Western Digital WD SN5100 4 TB (this drive): 6,900 MB/s read, 6,700 MB/s write
In burst use the drive behaves as the ratings promise: game installs, library moves and large file copies ride the nCache 4.0 pseudo-SLC buffer at near-rated speed — Tom's Hardware recorded about 6.45 GB/s holding for over 78 seconds on the 2 TB model's cache, which exceeds 500 GB. The QLC trade arrives when the cache empties: sustained writes settle around 400 MB/s by TechPowerUp's measurement, adequate for archive duty, slow for daily video workloads. Random performance stays strong for QLC, and the power profile — roughly 4 watts active, 4 milliwatts idle — keeps a 4 TB payload gentle on laptop batteries and small-build thermals. At this capacity the 1,200 TBW endurance rating is the quiet headline: bulk storage that does not trade away its warranty.
Western Digital WD SN5100 vs Competitors
See how the WD SN5100 stacks up against other M.2 4.0 x 4 drives in our database:
Compare with rival drives:
Endurance, TBW & Warranty
Western Digital covers the SN5100 4TB for five years or 1,200 TBW of writes, whichever arrives first — the family maximum, running 300 TBW at 500 GB, 600 TBW at 1 TB and 900 TBW at 2 TB. At 40 GB of daily writes the budget stretches past eighty years; at 80 GB daily it still clears four decades, so the calendar term is the practical limit. Tom's Hardware framed the rating as a warranty boundary rather than an expected failure point, relevant context for QLC flash, whose four-bit cells wear faster than TLC. Note the per-terabyte arithmetic: 1,200 TBW across 4 TB equals 300 TBW per terabyte, half the allowance of the 500 GB and 1 TB models — still generous in absolute terms. Claims run through Western Digital's standard support channels with proof of purchase.
Western Digital WD SN5100 4 TB Specifications
| Category | Value |
|---|---|
| Capacity [?] | 4 TB |
| Interface [?] | M.2 4.0 x 4 |
| Controller [?] | SanDisk Polaris 3 |
| Memory type [?] | BiCS8 218-layer 3D QLC |
| DRAM [?] | No |
| Read speed (MB/s) [?] | 6900 |
| Write speed (MB/s) [?] | 6700 |
| Read IOPS [?] | 900000 |
| Write IOPS [?] | 1100000 |
| Endurance (TBW) [?] | 1200 |
| MTBF (million hours) [?] | n/a |
| Warranty (years) [?] | 5 |
Verdict: Is the WD SN5100 Worth It in 2026?
The Western Digital WD SN5100 4TB is the bulk-storage play in the fastest QLC platform TechPowerUp has ever tested: 6,900/6,700 MB/s ratings, 1,200 TBW of endurance and five years of warranty across four terabytes of single-sided QLC. Skip it for sustained professional writes — the WD Black SN850X 4 TB and its DRAM cache handle that discipline, and the TLC-based WD Black SN7100 remains the better all-round drive at smaller sizes. Crucial's P3 Plus is the slower QLC alternative when cost alone drives the decision. For a Steam library, console expansion or project archive that needs size first and burst speed second, though, PCMag's finding of strong performance across most benchmarks carries here: this is the most sensible large-capacity SN5100.
+ Pros
- 1,200 TBW endurance, the family maximum
- 6,900 MB/s reads and 6,700 MB/s writes rated
- 4 TB on a single-sided M.2 2280 board
- 5-year warranty across the whole family
- 4 mW idle draw for laptop use
- Fastest QLC platform in TechPowerUp testing
- Cons
- Read rating dips to 6,900 MB/s from 7,100
- Post-cache writes fall to roughly 400 MB/s
- 300 TBW per terabyte, half the small-capacity allowance
- No DRAM cache; HMB only
- Needs an aftermarket heatsink for PS5 use
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