Processor and memory capabilities of Windows XP Professional x64 Edition and of the x64-based versions of Windows Server 2003

The number of processors and the amount of physical RAM that are supported

The following table compares the number of processors and the amount of physical RAM that are supported by the x64-based versions of Windows Server 2003 and by Windows XP Professional x64 Edition to those that are supported by the 32-bit versions.

Operating system	Number of processors	Physical RAM
Microsoft Windows Server 2003, Standard Edition	4	4 gigabytes (GB)
Microsoft Windows Server 2003, Standard x64 Edition	4	32 GB
Microsoft Windows Server 2003, Enterprise Edition	8	64 GB
Microsoft Windows Server 2003, Enterprise x64 Edition	8	1 terabyte
Microsoft Windows Server 2003, Datacenter Edition	32	64 GB
Microsoft Windows Server 2003, Datacenter x64 Edition	64	1 terabyte
Microsoft Windows XP Professional	2	4 GB
Microsoft Windows XP Professional x64 Edition	2	128 GB

Notes 

• x86-based versions of Windows Server 2003 that are running on a computer that uses a multicore processor or a hyper-threading processor support a maximum number of 32 logical processors.
• x64-based versions of Windows Server 2003 that are running on a computer that uses a multicore processor or a hyper-threading processor support a maximum number of 64 logical processors.

Memory allocation settings

The following table compares the memory allocation settings that are supported by the x64-based versions of Windows Server 2003 and Windows XP Professional x64 Edition to those that are supported by the 32-bit versions.

Memory allocation settings	32-bit versions	x64-based versions
Total amount of virtual address space	4 GB	16 terabytes
Amount of virtual address space per 32-bit process	2 GB (3 GB if the /3GB switch is added to the Boot.ini file)	2 GB (4 GB if the /LARGEADDRESSAWARE option is used)
Amount of virtual address space for the 64-bit processes	Not applicable	8 terabytes
Amount of paged pool memory	470 megabytes (MB)	128 GB
Amount of non-paged pool memory	256 MB	128 GB
Size of system cache	1 GB	1 terabyte

For more information about the x64-based versions of Windows Server 2003, visit the following Microsoft Web site:

http://www.microsoft.com/windowsserver2003/64bit/default.mspx

For more information about Windows XP Professional x64 Edition, visit the following Microsoft Web site:http://www.microsoft.com/windowsxp/64bit/default.mspx