Side-by-side specifications of the Synology FS6400 and FS6420, from official datasheets. Differences are highlighted.
| FS6400 | FS6420 | |
| CPU | 2x Intel Xeon Silver 4110 | AMD EPYC 7303 |
| Cores / threads | 16c/32t | 16/32 |
| RAM (base) | 32 GB | 64 GB |
| RAM (max) | 512 GB | 1024 GB |
| Drive bays | 24 | 24 |
| Expandable to | 72 | — |
| M.2 slots | 0 | — |
| Network | 2x 1GbE + 2x 10GbE RJ-45 | 2x 10GbE RJ-45 |
| 10GbE | yes | yes |
| Max raw capacity | 184.32 TB | 1 PB |
| Hot-swap | yes | yes |
| Form factor | rackmount | 2U rackmount |
| Released | 2025 | 2026 |
Choose the FS6420 if you want the newer Intel Xeon Silver CPU, a higher 256 GB RAM ceiling, 24 bays with expansion support, built-in dual 10GbE, and M.2 slots for cache. Pick the FS6400 only if you’re buying an older platform and can live with its lower RAM ceiling, 24-bay base but less modern expansion/networking, and no M.2 cache support.