Western Digital WD Black SN7100 1TB VS Western Digital WD Blue SN5100 500GB

Both drives deliver strong read performance, but the WD Black SN7100 1TB holds a clear edge across the board. Its 7250 MB/s sequential read speed outpaces the WD Blue SN5100 500GB's 6600 MB/s by roughly 10% — a gap that becomes tangible when transferring large files such as 4K video projects or disk images, where sustained throughput directly translates to waiting less.

The random read gap is even more pronounced: the SN7100 reaches 1,000,000 IOPS versus the SN5100's 660,000 IOPS — a difference of over 50%. Random read performance governs how snappy a system feels during everyday tasks like launching applications, booting the OS, or loading game assets, since these workloads consist of thousands of small, scattered reads rather than one continuous stream. A drive with higher IOPS handles these bursts more efficiently, reducing micro-stutter and latency under mixed workloads.

The SN7100 has a clear advantage in this category. While both drives are fast enough for mainstream use, the SN7100's superior sequential and — especially — random read speeds make it the stronger choice for users running demanding workloads, high-performance gaming rigs, or creative pipelines where read responsiveness matters.

On the write side, the WD Black SN7100 1TB again leads, posting a sequential write speed of 6900 MB/s against the WD Blue SN5100 500GB's 5600 MB/s — a roughly 23% advantage. In practice, this matters most when writing large volumes of data continuously: exporting a video render, cloning a drive, or moving a sizeable game library. The wider the gap in sequential write speed, the more time saved on these bulk operations.

Random write performance tells a similar story. The SN7100's 1,400,000 IOPS versus the SN5100's 1,100,000 IOPS represents a ~27% lead — meaningful for workloads that scatter small writes across the drive simultaneously, such as database operations, software compilation, or running virtual machines. Sustained random write capability also influences how gracefully a drive handles background tasks while the system remains responsive under load.

The SN7100 takes the edge in this category decisively. Both drives are competitive at their respective tiers, but across sequential and random write metrics, the SN7100 consistently outperforms the SN5100 by a margin large enough to matter in any write-intensive scenario.

Beneath the shared M.2 PCIe 4.0 form factor and identical controller channel counts, the most consequential difference here is NAND flash type. The WD Black SN7100 uses TLC (Triple-Level Cell) storage, while the WD Blue SN5100 relies on QLC (Quad-Level Cell). TLC stores three bits per cell versus QLC's four, which translates directly to better sustained write performance, lower write amplification, and greater long-term cell endurance — advantages that compound over years of daily use. For write-heavy workloads, TLC is the more resilient architecture.

Endurance figures reflect this difference proportionally: the SN7100 is rated for 600 TBW against the SN5100's 300 TBW, but since the SN7100 also has twice the capacity, the per-gigabyte endurance is effectively identical. One genuine surprise is that the SN5100 carries the newer NVMe 2.0 specification versus the SN7100's NVMe 1.4 — though in practice, NVMe 2.0 introduces features largely relevant to enterprise and data center use cases, so this distinction is unlikely to matter for most consumer workloads.

Overall, the SN7100 holds the edge in this category, primarily due to its TLC NAND, which offers a more durable and consistent foundation for demanding use. Both drives share the same warranty period, interface, and cache mechanism, making the flash type the defining factor for users prioritizing longevity and sustained performance.