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 |
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Entries (RSS)
April 23rd, 2009 09:43
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.
March 30th, 2009 22:32
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
September 25th, 2008 15:06
i dont know about computer but now i will
July 18th, 2008 13:58
It is possible? 2003 server standard edition 32 bit supports 8gb ram with PAE
July 11th, 2008 01:13
According to http://support.microsoft.com/kb/888732
Microsoft Windows XP Professional x64 Edition supports 128GB, not 4GB.
June 7th, 2008 01:34
[...] 1: Enable PAE support on Windows Server to allow large segment of physical memory to be [...]
June 4th, 2008 18:00
[...] Via | Tip and Trick [...]
June 2nd, 2008 02:48
Not a standard edition of Win2k3.
June 1st, 2008 09:14
Windows Server 2003 do support more than 4GB with PAE enabled.
June 1st, 2008 07:28
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.
June 1st, 2008 01:37
[...] to have large memory size, typically bigger than 4 GB. Which mean that on 32-bit operating system, PAE has to be enabled, although neither Lock Pages in Memory nor AWE depend on PAE. Beside, on 32-bit operating systems, [...]