: Standard rear panels usually include Ethernet (RJ-45), USB 2.0, and occasionally USB 3.0. Common Maintenance Procedures
If you lost the physical manual, here is the default Intel configuration for the 21-series layout:
Typically 2 DDR3 SDRAM slots, supporting up to 16GB of RAM. Expansion: 1x PCI Express x16 slot for dedicated graphics.
The marking "21 B6 E1 E2" (often preceded by a slash as /21-B6-E1-E2