Dell 2355 Mono Laser User Manual page 302

Press the memory module into the slot with care until you hear a "click".
5
NOTE:
The notches and grooves illustrated above may not match those on an actual DIMM
and its slot.
Replace the control board cover.
6
Reconnect the power cord and printer cable, and turn the printer on.
7
After installing the memory DIMM, printer drivers will automatically configure the
updated memory.
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