Side-by-side specifications of the Synology RS816 and RS818+, from official datasheets. Differences are highlighted.
| RS816 | RS818+ | |
| 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 DDR3 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 (optional M2D18 adapter) |
| Network | 2x Gigabit Ethernet | 4 x 1GbE RJ-45 |
| 10GbE | no | optional |
| Max raw capacity | 56 TB | 80 TB raw with RX418 (4 x 10 TB internal plus expansion) |
| Hot-swap | yes | yes |
| Form factor | 1U rackmount | 1U rackmount |
| Released | 2016 | 2018 |
| Power consumption | — | 45.28 W / 20.81 W |
| DSM at launch | — | — |
Choose the RS818+ if you need substantially more performance: it has a quad-core Intel C3538 CPU, up to 32GB RAM, and supports a 10GbE NIC, versus the RS816’s Annapurna Labs quad-core CPU, 2GB maximum RAM, and 1GbE. Both are four-bay units with no M.2 SSD slots; the RS818+ adds expansion via a DX517 for up to nine drives, while the RS816 does not.