Side-by-side specifications of the Synology RS818+ and RS818RP+, from official datasheets. Differences are highlighted.
| RS818+ | RS818RP+ | |
| CPU | Intel Atom C2538, 2.4 GHz | Intel Atom C2538, 2.4 GHz |
| Cores / threads | 4 cores / 4 threads | 4 cores / 4 threads |
| RAM (base) | 2 GB DDR3 non-ECC SODIMM | 2 GB DDR3L non-ECC SODIMM |
| RAM (max) | 16 GB | 16 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 adapter |
| Network | 4 x 1GbE RJ-45 | 4 x 1GbE RJ-45 |
| 10GbE | optional | optional |
| Max raw capacity | 80 TB raw with RX418 (4 x 10 TB internal plus expansion) | 40 TB internal; 80 TB with RX418 |
| Hot-swap | yes | yes |
| Form factor | 1U rackmount | 1U rackmount |
| Released | 2018 | 2018 |
| Power consumption | 45.28 W / 20.81 W | 45.73 W / 21.79 W |
| DSM at launch | — | — |
Pick the RS818RP+ only if you need redundant power supplies; otherwise the RS818+ is usually the better value. Both use the same CPU class (Intel Atom C2538), have 4 bays and no native M.2 support, and can be expanded with the same 8-bay RX418; neither has built-in 10GbE. The main practical difference is memory headroom: RS818RP+ tops out at 16GB ECC, while RS818+ supports up to 2GB stock unless you’re using a different hardware revision—so verify the exact unit before buying.