1. What MOBO?
2. What EXACT RAM - need links.
3. Are you partitioning your HDD? If so any partitions have a 32-bit OS?
IF your MOBO has Memory (Hole) Remapping -> Enable ; use for 64-bit OS.
IF you have a Pirated copy of Windows 7 64-bit then it is in reality a 32-bit OS; if so see -> http://www.cristgaming.com/pirate.swf
Please post the following image: