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CAD tip CAD tip # 5551:

Question CAD 
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Q - question

Enabling the /3GB mode in Windows Vista and Win7.

A - answer If you get a "not enough memory", "out of memory", "low memory" or a similar type of RAM error in a Windows Vista or Win7 application...

Windows Vista and Windows 7 no longer use the BOOT.INI file, so there is a different method for setting the "3GB" switch which enables to use 3GB of RAM for applications in 32-bit Windows (otherwise they use just 2GB - maximum).

If you want to make accessible 3GB RAM for your CAD applications in Vista/Win7, use the BCDedit.exe tool (Boot Configuration Data Editor). The 3GB memory mode can be enabled with the command:

bcdedit /set IncreaseUserVa 3072
and disabled by the command:
bcdedit /deletevalue IncreaseUserVa
Run this command from a command window with Administrator priviledge - i.e. (in the Start menu) type CMD and press Ctrl+Shift+Enter, or select "Command Prompt" (Accessories), right-click on it and choose "Run as Administrator".

Restart your PC after this change.

CAD Studio recommends using 64-bit versions of OS and CAD software to solve RAM problems.

100% Vista,Win7  CAD,HP 
6.5.2007    120069×   FAQ  
applies to: AutoCAD · Inventor · Revit · AutoCAD Architecture · Civil 3D ·

See also:
Tip 12524:Overview of Revit runstring parameters (for Revit.exe)
Tip 8493:Missing context menus and toolbars in Inventor 2012.
Tip 6617:Error AcMapCoordinateTransform.cpp when inserting an image.
Tip 6564:AutoCAD reports FATAL ERROR: Out of memory - shutting down
Tip 5948:Maximum addressable memory in the individual Windows versions.

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