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 | 0 | 4 via RX4 |
| M.2 slots | 0 | 0 |
| Network | 2x Gigabit | 2 x Gigabit |
| 10GbE | no | no |
| Max raw capacity | 4 TB | 8 HDDs |
| Hot-swap | yes | yes |
| Form factor | 1U rackmount | 1U rackmount |
| Released | — | 2009 |
| Power consumption | 69.5 W / 25 W | 28 W / 9.5 W |
| DSM at launch | — | 2.1 |