Side-by-side specifications of the Synology DS1813+ and DS1815+, from official datasheets. Differences are highlighted.
| DS1813+ | DS1815+ | |
| CPU | Intel Atom D2700 | Intel Atom C2538 |
| Cores / threads | 2C/4T | 4 cores / 4 threads |
| RAM (base) | 1GB | 2 GB |
| RAM (max) | 4GB | 6 GB |
| Drive bays | 8 | 8 |
| Expandable to | 10 | 10 |
| M.2 slots | 0 | 0 |
| Network | 4x GbE | 4x Gigabit |
| 10GbE | no | optional |
| Max raw capacity | 72TB | 48 TB |
| Hot-swap | yes | yes |
| Form factor | desktop | desktop |
| Released | 2013 | 2015 |
Pick the DS1815+ if you want the newer Atom C2538 CPU, more RAM headroom, and better scaling: it supports up to 6 GB RAM versus 4 GB on the DS1813+, keeps 8 bays, and can expand to 17 bays with the DX513. Neither model has built-in 10GbE or M.2, so those aren’t deciding factors here.