Dell XPS 14 (L421X, Mid 2012) - Manual (Page 30)

Postrequisites
1 Replace the battery. See "Replacing the Battery" on page 26.
2 Replace the speakers. See "Replacing the Speakers" on page 24.
3 Follow the instructions from step 2 to step 6 in "Replacing the Base Cover" on
page 15.
4 Turn on the computer.
As the computer boots, it detects the memory module(s) and automatically updates
the system configuration information.
To confirm the amount of memory installed in the computer:
Click Start
→ Control Panel→ System and Security→ System.
30 | Replacing the Memory Module