Best SATA SSDs for Synology DS423+ in 2026

Best SATA SSDs for the DS423+

Three sensible tiers depending on budget and how much of the four bays you want in flash.

Which should you pick

Why SATA SSDs make sense here, and where they don't

The DS423+ has no free M.2 NVMe slots for cache once you've decided to run all four bays as SATA SSDs, because this model's two M.2 slots are cache-only and not usable as extra storage bays. That's fine if you're building an all-flash array in the four main bays, since you get SSD-level random I/O and near-silent running without needing the NVMe slots at all. What you won't get is SSD-level network throughput, because two 1GbE ports cap you at roughly 220-230MB/s combined even with link aggregation, well short of what four SATA SSDs in RAID5 or RAID10 can actually deliver internally.

That mismatch matters for how you plan the build. If your goal is fast local access for a handful of clients doing file transfers, SSDs in this chassis mostly buy you low latency and quiet running rather than raw bandwidth. If your goal is maximum capacity for archives, film libraries, or Time Machine style backups, SATA HDDs at 4TB, 8TB or beyond will get you a lot further per pound, and you can then use the two NVMe slots as a proper read/write cache to smooth out random access.

Endurance is the other practical consideration. These are consumer QLC and TLC drives, not enterprise write-intensive parts, so they suit read-heavy NAS duty (media serving, general file storage, Time Machine) far better than a workload doing constant heavy rewrites, such as a busy VM datastore or a database under load.

Plex and Jellyfin: don't expect hardware transcoding