Side-by-side specifications of the Synology RS812 and RS812+, from official datasheets. Differences are highlighted.
| RS812 | RS812+ | |
| CPU | Intel Atom Dual Core 2.13 GHz | Intel Atom Dual Core 2.13 GHz |
| Cores / threads | 2 | 2 |
| RAM (base) | 1GB | 1GB |
| RAM (max) | 3GB | 3GB |
| Drive bays | 4 | 4 |
| Expandable to | 8 | 8 |
| M.2 slots | 0 | 0 |
| Network | 2x Gigabit | 2x Gigabit |
| 10GbE | no | no |
| Max raw capacity | 16TB | 24TB |
| Hot-swap | yes | yes |
| Form factor | 1U rackmount | 1U rackmount |
| Released | 2012 | 2012 |
Choose the RS812+ if you want materially better headroom: it has a faster CPU, higher RAM ceiling, and can use 10GbE expansion; the RS812 is the lower-end model. Both are 2-bay units with no M.2 support and no built-in expansion beyond the two bays, so for a simple 2-bay file server the RS812 is the cheaper pick.