Recently we did some memory upgrade on one of our server pc. It had 2 GB of RAM and we upgrade it to 6 GB . As you know, 32 bit (known as x86) Operating System only support 3.2 GB RAM maximum. After installing RAM into system, In the BIOS it showed correct amount of memory, but in Windows OS (32bit) it shows only 3.2 GB of RAM as showed in the image below.
To fix this issue, add the following syntax at the end in boot.ini [(found in c:\) , in [operating systems] section.
Windows 2003 boot.ini sample
[boot loader] timeout=30 default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS [operating systems] multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windows Server 2003, Enterprise" /noexecute=optout /fastdetect /PAE
Save & exit. Now reboot the system and this time, you will see proper result. as showed in the image below