adding memory results in less usable memory

i have a new HP Z400 workstation. it has a new install of windows 7 enterprise 64bit with all updates. the pc came with 6gb of ram installed. i purchased 6gb of kingston memory that was specifically listed for this workstation. the ram is installed as 6 x 2gb modules. slot 1 factory module slot 2 kingston module slot 3 factory module slot 4 kingston module slot 5 factory module slot 6 kingston module. when this pc just had the factory modules it shows 6 gb installed 5.83 usable. it now shows 12gb installed with only 3.23 usable. what is causing the decrease in usable memory as well as what is causing the usable memory to be a fraction of the installed memory?

HP is working on a bios revision. the bios revision in the pc (which is the current revision) has issues with memory addressing. that said there is a workaround to getting usable memory to be consistent with installed memory. it involves the msconfig file (I did not run any memtests. all of the memory modules are fine).

a simple, and painless, way to force windows to recognize correct usable memory is open msconfig by entering msconfig in a run command. go to the boot tab click advanced. uncheck maximum memory, reboot, open msconfig and check maximum memory, reboot.

this may not work for everyone but worked for me