I’m installing a HP ML 370 G5 server with Windows 2003 R2 SP2 and the server upgraded to 4 GB memory. After done all the installation and updates, i check the system memory and on the “General” tab only display 3.25 GB memory.

I wonder where does the rest goes? So i dig in google.com and search for solution then i found out that we need to enable the PAE (Physical Address Extension) option on the boot.ini file.

WINDOWS=”Windows Server 2003, Standard” /PAE /noexecute=optout /fastdetect

You just need to add in the “/PAE” portion to your existing boot.ini file and reboot your server then you can see the full physical memory size display on the “General” tab.

Source : The Old New Thing