# Western Digital WD SN5100 4TB Review — QLC Bulk Storage, Gen4 Speed (2026)

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.

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. 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.

## Specifications

| Specification | Value |
| --- | --- |
| Capacity | 4 TB |
| Interface | M.2 4.0 x 4 |
| Controller | SanDisk Polaris 3 |
| Memory type | BiCS8 218-layer 3D QLC |
| DRAM cache | No |
| Sequential read | 6900 MB/s |
| Sequential write | 6700 MB/s |
| Random read IOPS | 900000 |
| Random write IOPS | 1100000 |
| Endurance | 1200 TBW |
| MTBF |  |
| Warranty | 5 years |

## Performance

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.

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.

## 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.

## Pros and Cons

**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


## Verdict

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.

## Frequently Asked Questions

### Is the Western Digital WD SN5100 4TB good for a game library?

Yes — this is the capacity built for it. Four terabytes holds an operating system and dozens of 100 GB-plus titles, the 6,900 MB/s read rating keeps loads indistinguishable from faster drives, and installs arrive at multi-gigabyte rates through the pseudo-SLC cache before any QLC penalty appears. TechPowerUp's fastest-ever-Q verdict came from 2 TB testing, and PCMag's 4 TB review found the drive strong across most benchmarks. Treat it as a read-heavy library disk rather than a constant-write scratch disk and the QLC trade-off never registers.

### Is the Western Digital WD SN5100 4TB a good PS5 upgrade?

On paper, one of the better-priced ways to add 4 TB to a PS5. The drive is a PCIe 4.0 NVMe rated at 6,900 MB/s reads — above Sony's 5,500 MB/s guidance — in an M.2 2280 body within the console's dimension limits, and 4 TB suits a modern library. Two requirements apply: the drive ships without a heatsink, and Sony requires one, so add a slim plate that keeps the assembly under the 11.25 mm height allowance. SanDisk's product page makes no console claim, so treat the fit as criteria-based rather than officially listed.

### Does the Western Digital WD SN5100 have a DRAM cache?

No — all four capacities, including the 4 TB, are DRAM-less. SanDisk's Polaris 3 controller uses up to 64 MB of system memory through the Host Memory Buffer for mapping tables, confirmed by TechPowerUp's review, and SanDisk's nCache 4.0 technology runs the hybrid pseudo-SLC write cache that produces the family's strong burst numbers. For library, boot and desktop duty the design is effectively indistinguishable from DRAM-equipped drives; only sustained writes past the cache reveal the QLC underneath, settling to a few hundred megabytes per second.

### What is the TBW endurance of the Western Digital WD SN5100 4TB?

The 4 TB model is rated at 1,200 TBW under a 5-year limited warranty, whichever arrives first — the family maximum, running 300, 600, 900 and 1,200 TBW across 500 GB to 4 TB. At 40 GB of writes per day, the budget stretches past eighty years, so no consumer workload exhausts it; Tom's Hardware framed these ratings as warranty boundaries rather than failure predictions. Do note the per-terabyte allowance is 300 TBW, half of what the 500 GB and 1 TB models carry, a consequence of QLC density at this size.

### SN5100 4TB or WD Black SN850X 4TB?

Positioning decides. The SN850X is the DRAM-cached flagship: stronger sustained and random-write performance, better behavior under constant heavy writing, and a proven enthusiast track record — the pick for scratch disks and professional workloads. The SN5100 4TB counters with full Gen4 burst speed on QLC density, a single-sided board, 1,200 TBW of endurance and lower power draw. For a game library, console expansion or archive where burst reads dominate, the SN5100 does the same job; for write-heavy creative work, the SN850X earns its premium.

### Is QLC reliable enough for long-term archival storage?

For data retention and lifespan, yes, with reasonable caveats. The 1,200 TBW rating and 5-year warranty cover far more writing than an archive drive ever sees — at 40 GB per day the budget lasts decades — and Tom's Hardware noted these figures are warranty boundaries, not failure predictions. QLC's real weaknesses are sustained-write speed once the pseudo-SLC cache empties and somewhat tighter write endurance per cell than TLC, neither of which matters much for a drive that is written occasionally and read often. Keep backups regardless of NAND type; no SSD is an archive strategy by itself.

### How does the SN5100 4TB handle very large file transfers?

In two phases. Transfers up to several hundred gigabytes run at near-rated speed: Tom's Hardware's saturation test on the 2 TB sibling showed roughly 6.45 GB/s holding for more than 78 seconds on a pseudo-SLC cache exceeding 500 GB, and the 4 TB model's larger NAND pool supports a cache of similar scale. Once the cache exhausts on a continuous transfer, throughput settles around 400 MB/s by TechPowerUp's measurement — slower than any TLC drive, but faster than most QLC competitors and quick to recover once the folding process completes.

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Last updated: 2026-09-26. Source: https://ssdrive.net/western-digital-wd-sn5100-4-tb