So I dont think its an OS limitation. I have 2 sticks of 4GB each (kingston hyperX 1866mhz). I put the sticks on the DDR3_1 and DDR3_2 slots (Both grey). Windows says I have 8GB but only 3.97 usable. The I switch RAMs (just with each other, I didnt switch channels) and Windows says I can use 6.98GB. Its pretty strage because the usable amount chaged after I switched the RAMs, so that makes me think there isnt a broken stick or something like that. By the way, I have a Gygabite GA-970A-DS3P....
Usable RAM on 64 bit Windows
Usable RAM on 64 bit Windows
