Remove the DIMM slot cover as shown in this figure.
Note: Loosen the screws , but do not remove them.
Note: For ThinkPad X200, X200s, and X200si, if only one DIMM is used on the computer you are servicing, the card must be installed in SLOT-0 ([a]), but not in SLOT-1 ([b]).
For ThinkPad X200, X200s, and X200si:
For ThinkPad X201, X201i, and X201s:
When installing: Insert the notched end of the DIMM into the socket. Press the DIMM firmly, and pivot it until it snaps into the place. Make sure that it is firmly fixed in the slot and does not move easily.