Acer Altos R910 - Manual (Page 88)

3 System upgrade 78
3 Insert the standoff into the hole in the ARMC/3 or BMC module
connector (A). The standoff installs on the bottom side of the
module.
4 Attach the module to the connector and snap the standoff into
the matching hole on the mainboard (B).
5 Observe the post-installation instructions described on page 34.