Side-by-side specifications of the Synology RS816 and RS818RP+, from official datasheets. Differences are highlighted.
| RS816 | RS818RP+ | |
| CPU | Marvell ARMADA 385 88F6820 1.8GHz | Intel Atom C2538, 2.4 GHz |
| Cores / threads | 2 cores / 2 threads | 4 cores / 4 threads |
| RAM (base) | 1 GB DDR3 | 2 GB DDR3L non-ECC SODIMM |
| RAM (max) | 1 GB | 16 GB |
| Drive bays | 4 | 4 |
| Expandable to | 0 | 8 total with RX418 |
| M.2 slots | 0 | 0 built-in; optional M2D18 adapter |
| Network | 2x Gigabit Ethernet | 4 x 1GbE RJ-45 |
| 10GbE | no | optional |
| Max raw capacity | 56 TB | 40 TB internal; 80 TB with RX418 |
| Hot-swap | yes | yes |
| Form factor | 1U rackmount | 1U rackmount |
| Released | 2016 | 2018 |
| Power consumption | — | 45.73 W / 21.79 W |
| DSM at launch | — | — |
Choose the RS818RP+ if you need more headroom: it has a much faster CPU, more RAM headroom, and includes dual power supplies for better reliability. It also has the same 4 bays, but unlike either model it can handle expansion needs better overall; neither model has built-in 10GbE or M.2. The RS816 is the cheaper/basic option, with a weaker CPU and lower RAM ceiling, so it’s only the pick for light SMB use.