Dell XPS 15 (L502X, Early 2011) - Manual (Page 100)

100 System Board
9 Disconnect the USB board cable and speaker cable from the connectors on
the system board.
10 Turn the top cover over.
11 Remove the heat sink (see "Removing the Heat Sink" on page 91).
12 Remove the processor module (see "Removing the Processor Module" on
page 95).
13 Disconnect the AC-adapter cable from the connector on the system board.
14 Remove the six screws that secure the system board to the top cover.
1 USB board cable connector 2 speaker cable connector
1 2