Acer Altos R920 Series - Manual (Page 190)

Appendix B: Memory configuration 172
7 Press Y to confirm. The server reboots to activate the changes.
Single-channel mode
Single-channel mode is a failsafe mode when the installed memory
configuration is incompatible with dual-channel operation. In this
mode, only Branch 0, Channel 0 is operational with all other FBDIMMs
disabled automatically.
To configure memory to single-channel mode:
1 Run BIOS setup. See “Entering BIOS setup” on page 100.
2 Use the up and down arrow keys to select the Advanced menu.
3 Use the up and down arrow keys to select Memory
Configuration, then press Enter. The Memory Configuration
menu appears.
4 Use the up and down arrow keys to select Memory RAS and
Performance Configuration, then press Enter. The Memory RAS
and Performance Configuration menu appears.
5 Set the Select Memory RAS Configuration to RAS Disabled.
6 Press F10 to save changes and exit.
7 Press Y to confirm. The server reboots to activate the changes.