How to Enable PAE in x86 32-bit Windows Server 2003 and 2000 to Use More than 4GB RAM

In some scenario, you will need to upgrade the windows operating system RAM to more than 4GB. But, in normal circumstances, Windows 2000 (Datacenter Server or Advanced Server) or Windows 2003 server operating system, wont be able to use more than 4GB RAM event though more RAM modules have been installed. To enable

In 32-bit Windows operating system, there is one method to access memory above 4 GB and this method has been widely implemented which called Physical Address Extension (PAE). PAE is the added ability of the IA32 processor to address more than 4 GB of physical memory. The following operating systems can use PAE to take advantage of physical memory beyond 4 GB:

Microsoft supports Physical Address Extension (PAE) memory in Microsoft Windows 2000, Windows XP, and Windows Server 2003 products:

Operating system	Maximum memory support with PAE
Windows 2000 Advanced Server	8 GB of physical RAM
Windows 2000 Datacenter Server	32 GB of physical RAM
Windows XP (all versions)	4 GB of physical RAM*
Windows Server 2003 (and SP1), Standard Edition	4 GB of physical RAM*
Windows Server 2003, Enterprise Edition	32 GB of physical RAM
Windows Server 2003, Datacenter Edition	64 GB of physical RAM
Windows Server 2003 SP1, Enterprise Edition	64 GB of physical RAM
Windows Server 2003 SP1, Datacenter Edition	128 GB of physical RAM

To enable PAE in Windows Server 2003 and Windows 2000 (and Windows XP), append the /PAE switch to the end of the line of operating system in the Boot.ini file. To disable PAE, use the /NOPAE switch. The Boot.ini normally located in the root folder (i.e. C:\) with Read-Only and Hidden attributes, which are required to be removed before the file can be edited.

For example,

Original Boot.ini:

[boot loader]
timeout=0
default=multi(0)disk(0)rdisk(0)partition(1)\WINNT
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINNT=”Microsoft Windows 2000 Advanced Server”
/fastdetect

Change the Boot.ini to become:

[boot loader]
timeout=0
default=multi(0)disk(0)rdisk(0)partition(1)\WINNT
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINNT=”Microsoft Windows 2000 Advanced Server”
/fastdetect /PAE

Resources
1. http://support.microsoft.com/kb/283037
2. http://problemandsolutions.blogspot.com