Many of Autodesk's applications, including Navisworks, are able to take advantage of the 3GB functionality switch.
Advanced users may know that the virtual address space of processes and applications is still limited to 2 GB unless the /3GB switch is used in the Boot.ini file. When the physical RAM in the system exceeds 16 GB and the /3GB switch is used, the operating system will ignore the additional RAM until the /3GB switch is removed. This is because of the increased size of the kernel required to support more Page Table Entries.
Note: Only applications that use IMAGE_FILE_LARGE_ADDRESS_AWARE in the process header can take advantage of this functionality.
Enable the 3GB switch on Windows XP
- Right-click My Computer. Click Properties.
- In the System Properties dialog box, click the Advanced tab.
- On the Advanced tab, under Startup and Recovery, click Settings.
- In the Startup and Recovery dialog box, under System startup, click Edit. The Windows boot.ini file will be opened in Microsoft® Notepad.
- Create a backup copy of the boot.ini file. Note: Boot.ini files may vary from computer to computer.
Select the following line in the boot.ini file:
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP Professional" /fastdetect
- Press Ctrl+C to copy the line and then press Ctrl+V to paste it immediately below the original line.
Note: Your text string may be different from the text string in this solution, so be sure to copy the text string from your boot.ini file, and not the text string included here.
Modify the copied line to include “ /3GB”, as shown in the following example:
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP Professional 3GB" /3GB /fastdetect
Note: Do not overwrite any existing lines.
- Save and close the boot.ini file.
- Click OK to close each dialog box.
- Restart your computer.
- During startup, select the 3GB option. If you do not select the 3GB option, the system will default to the 2GB total memory setting.
Note: If problems occur during startup, you may need to update some of your drivers.
Enable the 3GB switch on Windows Vista
- Right-click Command Prompt in the Accessories program group of the Start menu. Click Run as Administrator.
- At the command prompt, enter "bcdedit /set IncreaseUserVa 3072"
- Restart the computer.
Disable the 3GB switch on Windows Vista
- Right-click on Command Prompt in the Accessories program group of the Start menu. Click Run as Administrator.
- At the command prompt, enter "bcdedit /deletevalue IncreaseUserVa"
- Restart the computer.
For more information on the 3GB switch, refer to the following Microsoft MSDN article:
Please note that only skilled Administrators or personnel should perform the above stated procedure. I cannot be held responsible for any problems occurring on your machine/s as a result of the afore stated.
As always, thorough research of the content and it's impact is highly recommended before proceeding.