1) The ram memory module slots are connected to the motherboard, by Circuit Traces. (Also known as Signal Traces) Simple explanation of a Circuit Trace is thin, flat, tiny copper wires, that go all over the motherboard.More in-depth explanation,
http://en.wikipedia.org/wiki/Printed_circuit_boardFollowing the circuit traces on the bottom of the motherboard, and going to that ram memory slot, do you see any breaks, or burn marks in any of the circuit traces?2) What is the condition of the contact pins in the bottom of the ram memory slot? (Flashlight is needed, and maybe a magnifying glass)Corroded, or damaged contact pins?3) All of the above is assuming, you have tried using a different ram memory module, in the defective ram memory slot.A ram memory module with 'corroded' gold plated contact pins, will not make a good contact in the ram memory module slot.(Use a pencil eraser to clean the contact pins of the ram memory module. BOTH sides.If using an eraser that is on the end of a pencil, and not a solid eraser, refrain from letting the metal band on the pencil touch the gold plated contact pins.Handle the ram memory module by the BODY. The Body is everywhere on the ram memory module, except the gold plated contact pins on the bottom.
http://en.wikipedia.org/wiki/File:Generic_DDR_Memory_%28Xytram%29.jpgThe Body is coated with a see-through protective plastic.Refrain from touching the gold plated contact pins.Use air to remove the eraser dust before reinstalling. You can use a can of compressed air for computers, if available, or air pressure from your mouth will be sufficient.For additional questions please post in a Comment.Regards,joecoolvette