Dell Alienware M14x R2 (Early 2012) - Manual (Page 30)

2 Slide the memory module firmly into the connector at a 45-degree angle,
and then press the memory module down until it clicks into place.
If you do not hear the click, remove the memory module and reinstall it.
NOTE: Your computer may not boot if the memory module is not installed properly.
1
2
3
4
1 memory-module connector 2 tab
3 notch 4 memory module
3 Slide the tabs on the memory-module cover into the slots on the
computer base and lower the memory-module cover into place.
4 Tighten the captive screws that secure the memory-module cover to the
computer base.
Postrequisites
1 Replace the battery. See "Replacing the Battery" on page 18.
2 Replace the base cover. See "Replacing the Base Cover" on page 16.
3 Follow the instructions in "After Working Inside Your Computer" on page13.
Memory Module(s) 32