Jun 1, 2008
Tip and Trick Editorial

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

After installing Windows 2000 (Datacenter Server or Advanced Server) or Windows 2003, system properties shows that only around 3.37 GB of physical memory (RAM) is available for application and system use, although 4 GB or more RAM modules have been installed, and BIOS can correctly identifies the full installed size of physical memory, which means that the motherboard and x86 or x64 CPU processor can support more than 4 GB of physical memory.

32-bit Windows operating system depends on PAE (Physical Address Extension) feature to use more than 4 GB of physical memory. On most Windows 2000 and Windows Server 2003 system, especially those run in NUMA mode on a NUMA-capable computer. PAE is disabled by default. PAE is enabled by default only if DEP (Data Protection Execution) is enabled on a computer that supports hardware-enabled DEP, or if the computer is configured for hot-add memory devices in memory ranges beyond 4 GB.

Thus, if PAE is not enabled in Windows 2000 and Windows Server 2003 (for example, if DEP is turned off by administrator), the system may not able to detect, identify and see more than 4GB memory, and will have to allocate slightly more than 3GB of memory for system and application only as some memory address space has to be reserved and mapped for system devices and peripherals.

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

For Bootcfg command, use:

bootcfg /raw "/pae" /A /ID 1

Restart the computer after modification to make the change effective.

Note that even with PAE enabled, there is still memory limit imposed by the operating system itself. The table below list the maximum memory support with PAE enabled for Windows 2000, Windows Server 2003 and Windows XP. Most 32-bit client based Windows operating system, such as Windows XP and Windows Vista (see way to use large memory of more than 4GB in 32-bit Windows Vista), has OS level limit that restricts the maximum amount of memory able to be used to 4GB.

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
  • Mark Crowther

    Live intelligence, Windows 8 should be in the shops in 2 years. One of Microsofts subsidiaries leaked out the anticipated liberation date over the weekend. Lets hope it pursues the Windows 7 evolution process.We do not wish to experience another Vista fiasco

  • James Bacon

    pretty useless article as at the final hurdle it doesn't tell you which account to add! doh! another timewaster!

  • http://www.battlesbailbonds.com James Battles

    The PAE boot ini works fine to raise page file but the window report at least so far is still 3.12 and also correct post of 4gb in bios. I was able to raise page to 4790 with a max of 5500 but could have gone higher I expect.

    I guess I am feeling my way along and will find out more. I think I need a bios upgrade because the award bios shows 4096 in the bios but at post it looks like 3200….. I will nail it down soon. I need to run vhd 2008 enterprise inside a win2k3 enterprise server for studies.

  • Netto

    O XPnão vem com a função /PAE ativada no boot.ini, é necssário ativa-la, para isso:

    1) Clique em INICIAR/EXECUTAR, digite CMD e clique em OK, depois;

    2) digite via comando CD e enter para ir para a raiz principal, depois;

    3) digite ATTRIB -H -A -R -S BOOT.INI

    4) digite EDIT BOOT.INI e logo após a linha multi (0) disk (0) rdisk (0) partição (1) WINNT = "Microsoft Windows XP Professional"

    /fastdetect, adicione /PAE, ficando assim:

    multi (0) disk (0) rdisk (0) partição (1) WINNT = "Microsoft Windows XP Professional"

    /fastdetect /PAE

  • http://aoofle.com mbah gendeng

    i dont know about computer but now i will

  • hari babu

    It is possible? 2003 server standard edition 32 bit supports 8gb ram with PAE

  • http://fitt.tychy.pl/ RaFi

    According to http://support.microsoft.com/kb/888732

    Microsoft Windows XP Professional x64 Edition supports 128GB, not 4GB.

  • Pingback: Optimize SQL Server 2000, 2005 or 2008 in Large RAM System by Locking Pages in Memory and AWE » My Digital Life

  • Pingback: Come utilizzare oltre 4 GB di RAM su Windows Server 2000 e 2003 - Geekissimo

  • Artem S. Tashkinov

    Not a standard edition of Win2k3.

  • admin

    Windows Server 2003 do support more than 4GB with PAE enabled.

  • Artem S. Tashkinov

    PAE is enabled by default in Windows XP and 2003 – no options are required in boot.ini.

    But both 32bit Windows XP and 32bit Win 2003 standard do not support more than around 3.3GB of RAM due to software limitations imposed by Microsoft. 32bit Linux supports up to 64GB of RAM just fine.

  • Pingback: Enable Lock Pages in Memory to Prevent Database Paging to Disk » Tip and Trick

Get latest updates via email: