In the Properties of Computer, it is displayed 4GB (2GB available) for example
The above symptom may occur on the following system:
All Idea Laptops
Under the following operating system:
Microsoft Windows 7
There is a special option in Windows 7 that limits the amount of available RAM.
It can be changed in:
Start -> msconfig -> Boot Tab -> Advanced Options.
There is an option "Maximum Memory" in which you can set the amount of available RAM. Check this option if not all RAM is available in the Properties of Computer.