Hi: I have an Intel-based server with a S5000VSA motherboard, 2 x Xeon E5320 CPU and 16Gb RAM. It has an Adaptec 3405 RAID Controller with a single RAID 5 Array configured. The server is running Hyper-V. BIOS reports the full 16Gb of RAM as available, but Windows reports only 12Gb of installed RAM (System Configuration). I believe that Windows can reserve RAM for hardware devices - I have another similarly configured server (Intel S5500 m/b) but without an Adaptec RAID controller, that has all memory available, so I'm wondering if it is related to the Adaptec RAID controller. Thanks, Scott

Hi, Yes, Windows may reserve some RAM for hardware devices, however, I don’t think it will eat almost 4GB RAM. It seems that there are some issue with the motherboard or the memories. The following posts discussed the similar issue, you can refer to: SBS 2008 total memory half of installed memory http://social.technet.microsoft.com/Forums/en-US/winservergen/thread/98f5dd04-71f2-44fc-ae06-d604f4e2c87f/ Server not recognizing my memory http://social.technet.microsoft.com/Forums/en-US/winservergen/thread/64139703-da2d-42d5-b94b-c5de8e0d84e2/ Best Regards, Vincent Hu

Thanks Vincent, I removed the memory, "shuffled" the chips and put them back in. Now I have 16Gb RAM available. Not sure whether there was a seating problem or there is a problem with a particiular memory chip, but it does appear to be hardware related. I'll have to monitor it and see how it goes. Regards, Scott