Sony PCV-MXS10 - Vaio Desktop Computer System Reference Manual page 51

Removing, Installing, and Replacing Components
9
Align the module over the appropriate socket, noting the location of
pin 1 on the module and pin 1 on the socket.
1 1 1 1
Pin 1 side
10
Carefully but firmly insert the edge of the module into the socket.
11
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.
Memory module (DIMM)
39
Latch