Dell Latitude C640 - Manual (Page 12)

NOTE: Memory modules are keyed, or designed to fit into their sockets, in only one direction.
NOTICE: The memory module must be inserted at a 45-degree angle to avoid damaging the connector.
2. Align the notch in the memory-module edge connector with the tab in the socket.
3. Slide the edge connector of the module firmly into the socket 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.
4. Replace the memory module cover and tighten the two captive screws.
Mini PCI Card
You must remove the Mini PCI card before the system board can be removed.
Removing the Mini PCI Card
NOTICE: Disconnect the computer and any attached devices from electrical outlets, and remove any installed
batteries.
NOTICE: To avoid ESD, ground yourself by using a wrist grounding strap or by touching an unpainted metal surface on
the computer.
NOTICE: Read " Preparing to Work Inside the Computer " before performing the following procedure.
1. Remove the memory module cover , which also covers the Mini-PCI card.
2. Disconnect the Mini PCI card from the antenna cables.
3. To release a Mini PCI card from its socket, spread apart the metal securing tabs until the card pops up slightly.
4. Lift the Mini PCI card out of its connector.