I just recently built a Core i7 rig, and i happened upon a OEM windows 7 ultimate 64-bit disk that i am running as the OS. I have 12 gigs of Ram and windows reports that it has 12 but shows that only 10 gigs are usable and that 2 are in hardware reserve. I know this isnt a big issue just curious as to why. I have rarely spiked past 8 GB in some very large AutoCAD drawings. while extracting files and transferring data.