The 32-bit version of Windows has limits imposed on memory by Microsoft, usually 4GB on a desktop. To get around this, you will either have to use PAE or switch to a 64-bit version of the OS. I would not recommend the former, as PAE tends to have a slight performance hit, and it will require some sort of advanced hack.
According to this page, the 32-bit version of Windows 8 can only USE up to 3GB of RAM. The reason that you are not being able to use all 3 GB's is because the integrated graphics controller takes up a certain amount of RAM, which becomes unusable for anything other than the graphics controller.
Intel graphics do not have dedicated memory but utilizes some of the
computer's system memory. The amount of memory used for graphics may
be a fixed amount or may vary up to a maximum amount. It depends on if
the computer manufacturer has configured the computer to use a fixed
amount, a dynamic amount (varying up to a maximum amount), or a
combination of both fixed and dynamic amounts of graphics memory.
According to the manual for the dv6:
Intel Extreme Graphics - Intel GMA 4700MHD - Up to 1759 MB of graphics
subsystem memory on computer models equipped with 4096 MB of main
system memory (64-bit OS)