  Which version of Server 2008 are you using?  The reason I asked for the version: Standard, SBS, and Web are limited to a maximum of 32GB of RAM.  Only Datacenter and Enterprise can use more than 32GB of RAM:[URL]#physical_memory_limits_windows_server_2008  
PER510 - just upgraded to 64MB, (4 x 16GB) only 32 show as usable. Memory settings are configured for Optimized. RDIMMS are in slots A1/B1 &A2/B2. I thought this should give me 64G.. I referenced the Hardware Owners Manual for the setup... What am I missing? Thanks -  WJ
PER510 Memory @ 50%