Side-by-side specifications of the Synology DS1511+ and DS1512+, from official datasheets. Differences are highlighted.
| DS1511+ | DS1512+ | |
| CPU | 1.8GHz dual-core | Intel Atom D2700 |
| Cores / threads | 2 cores / 2 threads | 2 cores / 4 threads |
| RAM (base) | 1GB | 1 GB |
| RAM (max) | 3GB | 3 GB |
| Drive bays | 5 | 5 |
| Expandable to | 10 (2× DX510) | 10 (2× DX510) |
| M.2 slots | 0 | 0 |
| Network | 2× Gigabit | 2× Gigabit Ethernet |
| 10GbE | no | no |
| Max raw capacity | 15TB | 60 TB |
| Hot-swap | yes | yes |
| Form factor | desktop | desktop |
| Released | 2011 | 2012 |
| Power consumption | 68 W / 30 W | 50.6 W / unknown |
| DSM at launch | — | 4.0 |
Choose the DS1512+ if you want the clearly newer, faster option: it moves to a faster Intel Atom CPU and doubles the RAM ceiling to 2 GB, while keeping the same 5-bay base and the same optional expansion support. The DS1511+ is the older pick; neither model has built-in 10GbE or M.2, so those are not deciding factors here.