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I have 4GB RAM installed. PAE is off. How do I tell the Windows 7 32-bit kernel to allocate 3GB virtual paging area to user mode and only 1GB to kernel space?

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up vote 4 down vote accepted

Start a command prompt with Administrative privileges (write cmd in the Start search and right-click cmd.exe and select Run as Administrator). Write the command bcdedit /set IncreaseUserVA 3072 This increases the user address space to 3GB and shrinks the kernel address space to 1GB.

Do take care: If you have a badly coded driver this change can cause it to crash.

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On Windows, you can add the /3GB flag to your boot.ini file to turn on OS level support. However, this will only allow applications that also have the appropriate flag (IMAGE_FILE_LARGE_ADDRESS_AWARE) turned on in their process header (see here for more details).

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This won't work on Windows Vista and higher. They don't have boot.ini. But that link does explain how it works on Windows Vista so thanks. – unixman83 May 8 '11 at 23:55

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