HP ProLiant DL580 G3 Server - Manual (Page 107)

Memory options 107
4.
Remove or install the DIMM.
IMPORTANT: Be sure to observe all DIMM installation
requirements for the desired memory mode.
IMPORTANT: DIMMs do not seat fully if turned the wrong way.
5.
Close the memory board.
IMPORTANT: Be sure that the locking switch is unlocked. The
memory board will not seat in the server if the locking switch is locked.
6.
Install the memory board.