Dell OptiPlex 5400 Service Manual page 27

Steps
1. Align the notch on the memory module with the tab on the memory-module slot.
2. Slide the memory module firmly into the slot at an angle and press the memory module down until it clicks into place.
NOTE: If you do not hear the click, remove the memory module and reinstall it.
NOTE: Repeat step 1 and 2 if there are two memory modules.
3. Align the tabs on the DIMM door with the slots on the system-board shield and snap into place.
Next steps
1. Install the back cover.
2. Install the cable cover
3. Install the stand.
4. Follow the procedure in
(optional).
After working inside your computer.
Removing and installing components 27