Apple Mac 8600 - Manual (Page 168)

Take Apart DRAM DIMMs - 70
Replacement Caution:
The DIMM is keyed so that it
fits into the DIMM slot only
one way. Be sure to align the
notches in the DIMM with
the small ribs inside the
slot.
Replacement Note:
Push
down firmly and evenly on
the DIMM until you hear it
snap into place.