I just installed a P7H55-M motherboard, an i7 870 CPU and 4x2GB sticks of DDR3 RAM. However my computer is only utilising 4gb. When I check the system specifications it says: Installed Memory: 8.00GB (3.97 GB usable). How do I solve this?
Are you sure it's 64 bit? Sounds very suspicious to me. Another thing to check is how much your integrated graphics are using. It's extremely unlikely that they're using 4GB, but you might as well check.
Having same problem with Windows 7-64 bits. Have turned on memory mapping feature in BIOS, but still can't use all my RAM.... Did you find a solution?