Hi , I have just upgraded my server from 2008 R2 Std Edition to Enterprise as I assumed this would resolve the issue 16gb RAM being visible but under My Computer the Server states only 8gb RAM is usable ? :( despite seeing 16gb RAM. Have also tried performing the following at the command prompt, then a reboot but it didnt work either. BCEDIT /SET PAE ForceEnable The Application now installed on the Server took several days to complete the Installation ( yes several days ) as its massive and had to be restarted due to 1-2 initial error's... not to mentioned having only 8gb RAM available. The Application now installed is very memory hungry and the more the better, Motherboard is a ASUS Server Board with 2 CPU's and Max RAM I can Install 32gb RAM. Look forward to the replies... Regards, Geoff. W

Hi, if you have Virtualization configuration enabled in BIOS, disabled it and reboot your server.Edoardo Benussi - Microsoft MVP Management Infrastructure - Systems Administration https://mvp.support.microsoft.com/Profile/Benussi Windows Server Italian Forum Moderator edo[at]mvps[dot]org

Are you using Memory Mirroring ? http://blogs.technet.com/b/askperf/archive/2010/08/20/the-mystery-of-the-missing-memory-or-it-pays-to-know-your-hardware.aspx Esteban

Hi Edoardo, I thought I would get an Email Alert when someone replied to my query, but didnt get anything hence the delay in replying to your suggestion. Will check later today as the server is in a different location and I dont have remote access right now. G

Hi Esteban, Thanks for the idea, will check that in the BIOS as well and reply later today. G

Hi, Thanks for your help and suggestions, the issue is now resolved. Although Windows could see the entire memory installed @ 16gb , it could only use 8gb of it which is why I thought the problem initially was in Windows 2008 with PAE etc... Problem was finally tracked to the BIOS, turns out 2 of the Memory Sticks although were the same speed + voltage the board didnt like them... removed the offending Memory take the Total RAM down to 12gb and both the BIOS and Windows recognise all of 12gb RAM. So I'm happy and will upgrade the memory to 16 or higher another time. Thanks once again for the support / suggestions. Regards, Geoff.