Side-by-side specifications of the Synology RS408 and RS409+, from official datasheets. Differences are highlighted.
| RS408 | RS409+ | |
| CPU | 800 MHz | — |
| Cores / threads | — | — |
| RAM (base) | 512 MB | — |
| RAM (max) | — | — |
| Drive bays | 4 | 4 |
| Expandable to | — | 8 |
| M.2 slots | 0 | 0 |
| Network | 2x Gigabit | 2x Gigabit |
| 10GbE | no | no |
| Max raw capacity | 4 TB | — |
| Hot-swap | yes | yes |
| Form factor | 1U rackmount | 1U rackmount |
| Released | 2008 | 2009 |