4GT Technical Reference

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

4GT Technical Reference

The technology called 4-gigabyte tuning (4GT), also known as application memory tuning, or the /3GB switch, is one of two technologies that increase the amount of physical memory available to user mode applications. The other technology is Physical Address Extension (PAE) X86. For more information about PAE X86, see PAE X86 Technical Reference.

4GT allows memory-intensive applications running on 32-bit versions of the Microsoft Windows Server 2003, Enterprise Edition, or Windows Server 2003, Datacenter Edition, operating systems to use 50 percent more virtual memory by making less virtual memory available to the operating system. This subject will provide an overview of 4GT along with an in-depth description of how 4GT works.


  • 4GT is not required on the 64-bit versions of the Windows Server 2003 family.

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