I have recently installed Windows 7 x64 on my desktop. I have installed 8 GB RAM on my computer. It shows 3.12 GB of RAM is usable into system properties and into Task Manager. Why is this happening so? Whether it was happening due to BIOS settings or some other issue? I am unable to figure out with this situation. Can anyone give me idea on this situation? I will really thankful to you. Thanks in advance.