Full RAM not usable..

I have recently added to 2GB DDR2 RAM to my PC. But from properties its showing that 4GB RAM installed but out of that only 2GB usable. Any help??

Having looked at your specs...I see you're running 7 32 bit. By default of the 32 bit OS...it will only use 3 to 3.5 gigs of RAM no matter how much you install. That's the limitation of the 32 bit OS. To use more RAM, you will need to upgrade to the 64 bit OS.

Yes I know that 32bit has a capacity to support upto 3.5GB. Anyway I formatted my system. Now its showing 3.2GB usable. Why not full 3.5GB usable??

Memory addressing. Everything on and connected to the motherboard, and is taken away from the 4 GB total. Also even if you installed 64 bit Windows you will still get the same amount of memory available as on 32 bit, unless the bios supports memory remapping. Reason being is that the chipset on that motherboard only supports up to 4 GB of ram,

ARK | Intel® Desktop Board DG31PR

which makes it run into this (for Vista but the exact same thing applies to Windows 7),

The system memory that is reported in the System Information dialog box in Windows Vista is less than you expect if 4 GB of RAM is installed

Okay I got it.. Thanks for this info..