System Memory(RAM) related issue

[masoomsahib]

i am using windows 7 x64 bit operating system.i have installed 5gb of ram on it.but it

says that only 2gb is usable.why is that?

 

[DeaconFrost]

What are the system specs, especially the motherboard? I'm assuming you have a 4 GB and a 1 GB stick installed. Where they both new to this system, or were you running one, and added the other?