Enable 4GT

Enabling 4-gigabyte tuning (4GT) increases the amount of physical memory available to memory-intensive applications running on Windows Server 2003, Enterprise Edition, or Windows Server 2003, Datacenter Edition.

To enable 4GT, add the /3GB parameter to the start-up lines in the boot.ini file by. For example:

[boot loader] timeout=5 default=multi(0)disk(0)rdisk(0)
partition(1)\WINNT  
[operating systems] multi(0)disk(0)rdisk(0)
partition(1)\WINNT="Microsoft Windows 2000 Professional" 
/fastdetect /3GB

Note:

Setting cache sizes with 4GT support allows the size of the main and temporary caches to be increased up to a combined total of 2GB.
With Windows platforms that support 4GT, a process can extend beyond the 2GB address space boundary, up to a total of 3GB. However, the total size of the two buffer caches cannot exceed 2GB. This is due to the Windows restriction that prevents a single memory allocation from crossing the 2GB boundary.