Side-by-side specifications of the Synology DS1511+ and DS1515+, from official datasheets. Differences are highlighted.
| DS1511+ | DS1515+ | |
| CPU | 1.8GHz dual-core | Intel Atom C2538 |
| Cores / threads | 2 cores / 2 threads | 4 cores / 4 threads |
| RAM (base) | 1GB | 2 GB DDR3 |
| RAM (max) | 3GB | 6 GB |
| Drive bays | 5 | 5 |
| Expandable to | 10 (2× DX510) | 10 (with DX513) |
| M.2 slots | 0 | 0 |
| Network | 2× Gigabit | 4 x Gigabit |
| 10GbE | no | no |
| Max raw capacity | 15TB | 30 TB internal; 90 TB with DX513 expansion |
| Hot-swap | yes | yes |
| Form factor | desktop | Desktop |
| Released | 2011 | 2015 |
| Power consumption | 68 W / 30 W | 72.5 W / 18.4 W |
| DSM at launch | — | — |