Usable RAM out of available problem! A known problem is when you you have insufficient amount of usable RAM. If i install 3X2 Gb RAM, only 4 Gb is usable. If i install 6X2 Gb RAM, only 8 Gb is usable. If i install 6X4 Gb RAM, only 16 Gb is usable. Whatever RAM i install, seems like a third portion of it is not being used and that just pisses me, like the rest you, probably.. Solutions have been tried to no avail: 1) update bios - did not help. 2) msconfig/boot/advanced options/maximum memory: check & uncheck - did not help. 3) set the RAM by default SPD (CL9 1.5V) and then by the recommended tested values (CL7 1.65V) - did not help. What is left to do? Is this a Windows 64 bit problem or a faulty motherboard? I know many people had or still have this annoyance.