Dell Inspiron 1521 (Mid 2007) - Manual (Page 154)

154
Adding and Replacing Parts
Replacing the DIMM B Memory Module
NOTICE:
To avoid electrostatic discharge, ground yourself by using a wrist
grounding strap or by periodically touching an unpainted metal surface (such as a
connector on the back of the computer).
1 Align the notch in the module edge connector with the tab in the
connector slot.
2 Slide the module firmly into the slot at a 45-degree angle, and rotate the
module down until it clicks into place. If you do not feel the click, remove
the module and reinstall it.
NOTE:
If the memory module is not installed properly, the computer may not boot.
No error message indicates this failure.
1 securing clips (2) 2 memory module
1 2