Sony PCV-LX920 - Manual (Page 60)

VAIO Slimtop System Reference Manual 48
Memory Module (DIMM) Slots
Both sides of each Dual Inline Memory Module (DIMM) look very
similar. The side with pin 1 has a small "1" to the left of pin 1. Be sure to
orient a DIMM correctly in the DIMM connector (a small triangle on the
connector indicates pin 1).
O
N 1 2
DIMM1
DIMM2
Indicates pin 1
Memory module (DIMM)
1