The NAND layer race just cleared 300. SK hynix announced last week that it has begun shipping the PQC21, the world’s first client SSD built on 321-layer QLC NAND flash, and Dell Technologies is getting the initial supply.
The PQC21 is a compact M.2 2230 drive with a PCIe Gen 4 interface, available in 1TB and 2TB capacities. The 321-layer stack uses SK hynix’s V9 generation 4D NAND, which bumps the layer count significantly from the prior 238-layer product. For comparison, Samsung is currently shipping 286-layer drives, Micron sits at 276 layers, and Kioxia and SanDisk are still at 218.
QLC stores four bits of data per cell, which maximizes capacity per unit area and keeps manufacturing costs lower than TLC. The trade-off is sustained write performance: QLC cells are slower to program than TLC or MLC, which is why the PQC21 incorporates SLC caching. A portion of the drive temporarily operates in faster single-bit mode to absorb incoming writes before transferring data to the main QLC array, smoothing out performance during typical workloads like app installs, file transfers, and OS updates. SK hynix has not released sequential speeds or IOPS figures for the PQC21, so taking the company’s performance claims at face value requires some patience for third-party testing.
The OEM-first approach is standard for new NAND generations. Dell will fold the PQC21 into upcoming laptops and AI PC configurations, with SK hynix indicating plans to “continuously expand partnerships with other major global customers” — likely meaning Lenovo, HP, and others will follow. Retail availability is a separate question and probably not imminent, but it gives a indication of where client SSD pricing and density could move once this NAND reaches volume production.
The PQC21’s 2230 form factor — thumbnail-sized, just 22mm by 30mm — is designed precisely for that class of product. Handheld gaming PCs, thin-and-light laptops, and compact desktops all rely on 2230 drives, making this a potentially high-volume segment.
For the enthusiast building a gaming rig today, none of this translates directly to cheaper drives on Newegg this week. What it does signal is that high-capacity, energy-efficient QLC NAND is now production-ready at scale, and that the supply chain for next-generation storage is ticking forward on schedule.