I'm using a Mac Pro (desktop) but running it exclusively in Windows XP 64-bit. Until recently, all 16 GB of RAM was working correctly. Now however only 8 GB of RAM shows up under system properties and DxDiag. However, CPU-Z from CPUID shows 8 slots of memory each with 2 GB (which is indeed what is loaded). Why is there this discrepancy and how can I make the machine use all of it again? Thanks.