WD Blue SN5100 - M.2 PCIe Gen4 NVMe SSD - 4TB

The WD Blue SN5100 is the successor to the SN5000, targeting creators and professionals who need high-throughput storage without paying for the WD_BLACK premium. It uses PCIe Gen 4 x4 with SanDisk QLC 3D CBA NAND and nCache 4.0 technology, delivering sequential reads up to 7,100 MB/s and writes up to 6,700 MB/s on the 1TB and 2TB models.

What Changed from SN5000

The SN5100 is roughly 30% faster than the SN5000 in sequential throughput (7,100 vs 5,500 MB/s read on the top models). Random performance also improved significantly, with the 1TB and 2TB models hitting 1M read and 1.3M write IOPS compared to the SN5000's 730K/770K. Endurance ratings stayed the same. Both use QLC NAND, but the SN5100 uses SanDisk's newer 3D CBA architecture.

Specs by Capacity

Capacity	Seq. Read	Seq. Write	Rand Read	Rand Write	TBW
500GB	6,600 MB/s	5,600 MB/s	660K	1.1M	300
1TB	7,100 MB/s	6,700 MB/s	1M	1.3M	600
2TB	7,100 MB/s	6,700 MB/s	1M	1.3M	900
4TB	6,900 MB/s	6,700 MB/s	900K	1.1M	1,200

The 500GB model takes a noticeable hit on read speeds and random IOPS due to fewer NAND dies for parallelism. The 4TB uses QLC throughout (no TLC cache tier difference), giving it slightly lower random read performance than the 1TB and 2TB.

QLC Considerations

All SN5100 models use QLC NAND, which stores four bits per cell. This enables high capacity at lower cost but means sustained write performance degrades once the SLC write cache (managed by nCache 4.0) fills up. For bursty creative workloads like photo editing, video imports, and project file copies, the cache handles the load well. For sustained sequential writes (e.g., continuously recording multi-stream video), the post-cache write speed will drop.

SN5100 vs. SN580

The SN580 uses TLC NAND with better sustained write consistency, but its sequential throughput caps at 4,150 MB/s. The SN5100 nearly doubles that. If your workload is read-heavy or burst-write (loading projects, copying files, launching applications), the SN5100 is the better choice. If you need consistent sustained writes, the SN580's TLC holds up better under pressure despite the lower peak speeds.

Best for: Creators and professionals who need fast reads and large capacity for media libraries, project files, and AI-assisted workflows.

Avoid if: You need sustained write endurance for continuous recording or write-heavy database workloads (consider the WD Black SN8100 or a TLC drive instead).