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Memory Limits for Windows Releases

This topic describes memory limits for supported Windows releases:

    * Memory and Address Space Limits
    * Physical Memory Limits: Windows Server 2008
    * Physical Memory Limits: Windows Vista
    * Physical Memory Limits: Windows Home Server
    * Physical Memory Limits: Windows Server 2003
    * Physical Memory Limits: Windows XP
    * Physical Memory Limits: Windows 2000

Limits on memory and address space vary by platform, operating system, and by whether the IMAGE_FILE_LARGE_ADDRESS_AWARE value of the LOADED_IMAGE [ http://msdn.microsoft.com/en-us/library/ms680349(VS.85,printer).aspx ] structure and 4-gigabyte tuning [ http://msdn.microsoft.com/en-us/library/bb613473(VS.85,printer).aspx ] (4GT) are in use.

Limits on physical memory for 32-bit platforms also depend on the Physical Address Extension [ http://msdn.microsoft.com/en-us/library/aa366796(VS.85,printer).aspx ] (PAE), which allows 32-bit Windows systems to use more than 4 GB of physical memory.
Memory and Address Space Limits

The following table specifies the limits on memory and address space for supported releases of Windows.
Memory type 	Limit in 32-bit Windows 	Limit in 64-bit Windows


User-mode virtual address space for each 32-bit process 	

2 GB

Up to 3 GB with IMAGE_FILE_LARGE_ADDRESS_AWARE and 4GT
	

2 GB

4 GB with IMAGE_FILE_LARGE_ADDRESS_AWARE
User-mode virtual address space for each 64-bit process 	

Not applicable
	

2 GB

    x64:  8 TB with IMAGE_FILE_LARGE_ADDRESS_AWARE

    Intel IPF:  7 TB with IMAGE_FILE_LARGE_ADDRESS_AWARE

Kernel-mode virtual address space 	

2 GB

From 1 GB to a maximum of 2 GB with 4GT
	

8 TB
Paged pool 	

Limited by available kernel-mode virtual address space or the PagedPoolLimit [ http://msdn.microsoft.com/en-us/library/bb870880(VS.85,printer).aspx ] registry key value.

Windows Vista:  Limited only by kernel mode virtual address space. Starting with Windows Vista Service Pack 1 (SP1), the paged pool can also be limited by the PagedPoolLimit registry key value.

Windows Home Server and Windows Server 2003:  530 MB

Windows XP:  490 MB

Windows 2000:  350 MB

	

128 GB

Windows Server 2003 and Windows XP:  Up to 128 GB depending on configuration and RAM.

Windows 2000:  Not applicable

Nonpaged pool 	

Limited by available kernel-mode virtual address space, the NonPagedPoolLimit [ http://msdn.microsoft.com/en-us/library/bb870880(VS.85,printer).aspx ] registry key value, or physical memory.

Windows Vista:  Limited only by kernel mode virtual address space and physical memory. Starting with Windows Vista SP1, the nonpaged pool can also be limited by the NonPagedPoolLimit [ http://msdn.microsoft.com/en-us/library/bb870880(VS.85,printer).aspx ] registry key value.

Windows Home Server, Windows Server 2003, and Windows XP/2000:  256 MB, or 128 MB with 4GT.

	

75% of RAM up to a maximum of 128 GB

Windows Vista:  40% of RAM up to a maximum of 128 GB.

Windows Server 2003 and Windows XP:  Up to 128 GB depending on configuration and RAM.

Windows 2000:  Not applicable

System cache virtual address space (physical size limited only by physical memory) 	

Limited by available kernel-mode virtual address space or the SystemCacheLimit [ http://msdn.microsoft.com/en-us/library/bb870880(VS.85,printer).aspx ] registry key value.

Windows Vista:  Limited only by kernel mode virtual address space. Starting with Windows Vista SP1, system cache virtual address space can also be limited by the SystemCacheLimit [ http://msdn.microsoft.com/en-us/library/bb870880(VS.85,printer).aspx ] registry key value.

Windows Home Server, Windows Server 2003, and Windows XP/2000:  860 MB with LargeSystemCache [ http://go.microsoft.com/fwlink/?LinkId=97918 ] registry key set and without 4GT; up to 448 MB with 4GT.

	

Always 1 TB regardless of physical RAM

Windows Server 2003 and Windows XP:  Up to 1 TB depending on configuration and RAM.

Windows 2000:  Not applicable

Physical Memory Limits: Windows Server 2008

The following table specifies the limits on physical memory for Windows Server 2008. Limits greater than 4 GB for 32-bit Windows assume that PAE is enabled.
Version 	Limit in 32-bit Windows 	Limit in 64-bit Windows
Windows Server 2008 Datacenter (full installation) 	

64 GB
	

2 TB
Windows Server 2008 Datacenter (Server Core installation) 	

64 GB
	

2 TB
Windows Server 2008 Enterprise 	

64 GB
	

2 TB
Windows Server 2008 Standard 	

4 GB
	

32 GB
Windows Server 2008 for Itanium-Based Systems 	

Not applicable
	

2 TB
Windows Web Server 2008 	

4 GB
	

32 GB
Physical Memory Limits: Windows Vista

The following table specifies the limits on physical memory for Windows Vista.
Version 	Limit in 32-bit Windows 	Limit in 64-bit Windows
Windows Vista Ultimate 	

4 GB
	

128 GB
Windows Vista Enterprise 	

4 GB
	

128 GB
Windows Vista Business 	

4 GB
	

128 GB
Windows Vista Home Premium 	

4 GB
	

16 GB
Windows Vista Home Basic 	

4 GB
	

8 GB
Windows Vista Starter 	

4 GB
	

Not applicable
Physical Memory Limits: Windows Home Server

Windows Home Server is available only in a 32-bit edition. The physical memory limit is 4 GB.
Physical Memory Limits: Windows Server 2003

The following table specifies the limits on physical memory for Windows Server 2003. Limits over 4 GB for 32-bit Windows assume that PAE is enabled.
Version 	Limit in 32-bit Windows 	Limit in 64-bit Windows
Windows Server 2003 Service Pack 2 (SP2), Datacenter Edition 	

128 GB

64 GB with 4GT
	

2 TB
Windows Server 2003 Service Pack 2 (SP2), Enterprise Edition 	

64 GB
	

2 TB
Windows Storage Server 2003, Enterprise Edition 	

8 GB
	

Not applicable
Windows Storage Server 2003 	

4 GB
	

Not applicable

Windows Server 2003 R2 Datacenter Edition

Windows Server 2003 with Service Pack 1 (SP1), Datacenter Edition
	

128 GB

16 GB with 4GT
	

1 TB

Windows Server 2003 R2 Enterprise Edition

Windows Server 2003 with Service Pack 1 (SP1), Enterprise Edition
	

64 GB

16 GB with 4GT
	

1 TB

Windows Server 2003 R2 Standard Edition

Windows Server 2003, Standard Edition SP1
	

4 GB
	

32 GB
Windows Server 2003, Datacenter Edition 	

128 GB

16 GB with 4GT
	

512 GB
Windows Server 2003, Enterprise Edition 	

32 GB

16 GB with 4GT
	

64 GB
Windows Server 2003, Standard Edition 	

4 GB
	

16 GB
Windows Server 2003, Web Edition 	

2 GB
	

Not applicable
Windows Small Business Server 2003 	

4 GB
	

Not applicable
Windows Compute Cluster Server 2003 	

Not applicable
	

32 GB
Physical Memory Limits: Windows XP

The following table specifies the limits on physical memory for Windows XP.
Version 	Limit in 32-bit Windows 	Limit in 64-bit Windows
Windows XP 	

4 GB
	

128 GB
Windows XP Starter Edition 	

512 MB
	

Not applicable
Physical Memory Limits: Windows 2000

The following table specifies the limits on physical memory for Windows 2000.
Version 	Limit in 32-bit Windows
Windows 2000 Professional 	

4 GB

Windows 2000 Server 	

4 GB
Windows 2000 Advanced Server 	

8 GB
Windows 2000 Datacenter Server 	

32 GB