Side-by-side specifications of the Synology RS1221+ and RS818+, from official datasheets. Differences are highlighted.
| RS1221+ | RS818+ | |
| CPU | AMD Ryzen V1500B | Intel Atom C2538, 2.4 GHz |
| Cores / threads | 4 cores / 8 threads | 4 cores / 4 threads |
| RAM (base) | 4 GB DDR4 ECC SODIMM | 2 GB DDR3 non-ECC SODIMM |
| RAM (max) | 32 GB | 16 GB |
| Drive bays | 8 | 4 |
| Expandable to | 12 total with RX418 | 8 total with RX418 |
| M.2 slots | 0 built-in; optional adapter card | 0 (optional M2D18 adapter) |
| Network | 4 × 1GbE RJ-45 | 4 x 1GbE RJ-45 |
| 10GbE | optional | optional |
| Max raw capacity | 108 TB single volume | 80 TB raw with RX418 (4 x 10 TB internal plus expansion) |
| Hot-swap | yes | yes |
| Form factor | 2U rackmount | 1U rackmount |
| Released | 2021 | 2018 |
| Power consumption | 49.89 W / 22.64 W | 45.28 W / 20.81 W |
| DSM at launch | — | — |