Epson AcuLaser C8600 Reference Manual page 240

3. Identify the DIMM slots.
4. Insert the DIMM into either slot. The two clips lock onto the
DIMM.
c
238 Using Options
Caution:
Do not force the DIMM into the slot.
Be sure to insert the DIMM facing the correct way.
You should not remove any modules from the circuit
board. Otherwise, the printer will not work.
DIMM slots