Side-by-side specifications of the Synology RS818+ and RS820+, from official datasheets. Differences are highlighted.
| RS818+ | RS820+ | |
| CPU | Intel Atom C2538, 2.4 GHz | Intel Atom C3538, 2.1 GHz |
| Cores / threads | 4 cores / 4 threads | 4 cores / 4 threads |
| RAM (base) | 2 GB DDR3 non-ECC SODIMM | 2 GB DDR4 non-ECC |
| RAM (max) | 16 GB | 18 GB |
| Drive bays | 4 | 4 |
| Expandable to | 8 total with RX418 | 8 total with RX418 |
| M.2 slots | 0 (optional M2D18 adapter) | 0 built-in; optional M2D18 via PCIe |
| Network | 4 x 1GbE RJ-45 | 4× Gigabit Ethernet |
| 10GbE | optional | optional |
| Max raw capacity | 80 TB raw with RX418 (4 x 10 TB internal plus expansion) | 56 TB raw (4×14 TB); 112 TB with RX418 |
| Hot-swap | yes | yes |
| Form factor | 1U rackmount | 1U rackmount |
| Released | 2018 | 2020 |
| Power consumption | 45.28 W / 20.81 W | unknown |
| DSM at launch | — | unknown |