Sony PCV-RX640 System Reference Manual page 51

Removing, Installing, and Replacing Components
9
Press down firmly and evenly at both corners until the module is
fully seated.
✍
When the module is fully seated, the handles on each side are straight up and
locked into the slot on each side of the module. If the handles are not totally
straight upright, continue to press down on each side of the module until the
handles lock into place.
10
Replace the power supply (see
page 48).
11
Replace the side cover (see
12
Reconnect the power cord and turn on the computer.
Your computer automatically recognizes the extra memory and will
configure itself accordingly when you turn on the computer. No further
action is required.
"Replacing the Power Supply"
"Replacing the Side Cover"
39
on
on page 25).