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Thread: The 3/Gig Switch! Is this safe to use!

  1. #1
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    Question The 3/Gig Switch! Is this safe to use!

    Hi! I recently installed the 3/Gig Switch so that I can use the other 2 Gigs that I put in! 4Gigs total! I am hearing differing views on this! Has anyone used it! Is it safe? Is there any problems with this line of code in the "boot.ini" file! I just lost my hardrive from uninstalling Inventor 10 Pro & am not sure if it was this 3/gig Switch file that caused the problem! We were unable to log onto my user settings. Using Win XP/Pro! TIA for any feedback on this one!
    Paul

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    Manufacturing Moderator jonathan.landeros's Avatar
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    Default Re: The 3/Gig Switch! Is this safe to use!

    Quote Originally Posted by prymal
    Hi! I recently installed the 3/Gig Switch so that I can use the other 2 Gigs that I put in! 4Gigs total! I am hearing differing views on this! Has anyone used it! Is it safe? Is there any problems with this line of code in the "boot.ini" file! I just lost my hardrive from uninstalling Inventor 10 Pro & am not sure if it was this 3/gig Switch file that caused the problem! We were unable to log onto my user settings. Using Win XP/Pro! TIA for any feedback on this one!
    Paul
    I haven't used the 3GB switch myself, but from the people I've talked to who've used it, it's pretty safe.

    The only warning is that you are changing your boot.ini file, so you want to make sure you have a restore point set to recover your system should things go wrong.

    I've only seen it happen one time, but I did see someone crash a machine to the ground by putting the 3GB line in the wrong place. Not to scare you out of doing it (I'd do it if I had the RAM to use), but caution is always a good thing here.
    Jonathan Landeros
    KETIV Technologies
    Orange County, California.

    I've got a blog: www.inventor-tales.blogspot.com

    “We have now left Reason and Sanity Junction.Next stop, Looneyville.” -Bob the Skull in the Dresden Files

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    Default Re: The 3/Gig Switch! Is this safe to use!

    Thanks Jonathan! Didn't seem like anyone was going to reply to this particular problem! I have used it successfully, but have had some trouble getting it going again! You have to be careful to leave a little extra Ram for the Operating system! This is done by further adding /userva 2900 to the line in the boot.ini or perhaps 2500 what ever works best. I also had to allow a paging file for virtual memory 4900! Have a good one!
    Paul

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    Default Re: The 3/Gig Switch! Is this safe to use!

    yoho, here some more feedback on the 3GB/ switch

    How can I improve capacity for large assemblies or drawings?
    Please note that Windows allocates Virtual memory to an application. This is the Address Space available to any application. The size of this Address space is a function of the design of the operating system, not the physical memory installed on the system. More physical memory will increase performance, but not address space. Inventor, like any Windows application, is limited by the address space allocated to it by the Windows Operating System. Whatever the limit, Inventor users may run into it. A warning will be issued when you reach 80% of the available address space. It is advisable to save your work as soon as possible. When windows issues a message that a memory request has been denied, Inventor is no longer intact.
    At the 80% warning, exit Inventor saving your results. Restart Inventor and re-load your work. This removes memory allocations that are no longer needed because that work has been accomplished.
    In a 32-bit computer (as Windows XP is) there is 4GB of memory address space.

    2GB of this address space is reserved for the system. 2GB is reserved for the applications. When you add the /3GB switch to the boot.ini, it is taking 1GB of available address space reserved for the OS and giving it to the applications.

    This can provide better performance for memory intensive programs like Inventor. However, there could be potential side-effects for the system of course. But nothing too much to worry about, or otherwise it would never be recommended.
    The boot.ini file is how you enable the option for the 3GB switch. It allows the 2GB that is dedicated to the system to give up 1GB and add it to the 2GB that is dedicated to the applications.

    See the example boot.ini file below:
    [boot loader]
    timeout=5
    default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
    [operating systems]
    multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect /NoExecute=OptIn
    multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional /3GB Switch" /3GB /fastdetect

    AND THE STATEMENT FROM AUTODESK

    Does Autodesk Inventor® support the /3GB switch on windows XP SP1 or newer?
    Autodesk Inventor® 7 and newer supports this option.
    Before enabling this mode, please check your workstation vendors web site for patches that may be needed for your system. HP is known to have some patches. Try searching on "3GB".
    Tip: When Autodesk Inventor® is running, Help > About shows if the workstation is configured for this option. This is useful if you do not know in which mode the workstation was booted.
    Tip: Before installing any driver (including a graphics driver) reboot the workstation to the standard 2GB mode, install the driver, and reboot to the standard 2GB mode so that the installation can finish.
    This switch is available on Windows XP Professional. Attempting to use it on Windows 2000 or NT4 will cause system instability.
    Be very careful setting up the 3GB option. If you do not leave yourself a way to boot in the standard configuration, you may have to reinstall windows.
    MS Windows was designed to use 4GB of address space total. Of this, 2GB is reserved for the operating system and 2GB for an application. Changing this balance reduces the amount available for the operating system. When running in this mode it is important to run as few applications as possible. This includes applications that may always run at startup.
    Go to Microsoft Knowledge base and search for "/3GB" for information on using the 3GB option on Windows XP.
    See this Knowledge Base article for tuning information that may be needed for some graphics cards. The ability to do this tuning was introduced in SP1 for XP, then immediately patched.
    The simplest way to enable the 3GB option is make a backup copy of the boot.ini file then, open the properties dialog of the c:\boot.ini file, remove the read only restriction, and edit it with notepad. See below for details.
    The boot.ini is a read only file. It is also a system file. Windows Explorer must be configured to show such a file before you can see it. In Windows Explorer, Tools> Folder Options > View select the following:
    "Hidden files and folders", click on "Show Hidden files and folders".
    Uncheck "Hide extensions for known file types" - Useful but not required.
    Uncheck "Hide protected operating system files (Recommended)" - OK this change.
    Then select boot.ini, right click, select properties, uncheck read only.
    Edit file
    You may wish to check read only when you are finished editing the file
    The 3GB option reduces the amount of kernel address space to 1GB. Sometimes the kernel may need more space for internal tables or other drivers. See Microsoft support for tuning information. If you have this problem, use "/USERVA=2900" (or 2800 etc.) (MB for this argument) to limit the USER Virtual Address space to less than 3GB. This allows more space for the operating system kernel if it is needed. This option is placed in the Boot.ini file just after the "/3GB" option.
    The first time you reboot to the 3GB mode immediately go the the My Computer properties > Advanced tab > Settings > Advanced tab > and change the maximum amount of virtual memory to 4 GB. This is part of the microsoft requirements.
    Graphics vendor specific information is available for these vendors:
    3Dlabs:
    The Wildcat III/4 cards do support the 3GB option.
    The Wildcat VP880 & VP990 use 256MB of kernel memory. The 3GB option reduces the amount of kernel address space to 1GB. If other devices are using large amounts of kernel memory, then this may cause a Wildcat VP driver to fail to load (see Microsoft support for tuning information). If you have problems, use set /USERVA=2900 (or 2800 etc.) to reserve an additional 100MB (or more if needed) for the kernel with these cards.
    ATI: The recommended mode of operation assumes that you have a 4GB system, a reasonable card (256MB or better) and setting the flag /userva=2500. See http://support.microsoft.com/?kbid=316739 for information on tuning your system so that stability is maintained.
    Matrox:
    Nvidia: The 3GB option appears to be supported by drivers newer than 4072. Using the latest drivers, no problems have been found with Nvidia cards. Not all cards were tested.
    NEC: Not tested
    My test system is set up as follows:
    1. multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP Professional" /fastdetect
    2. multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="XP full 3GB setting" /3GB /fastdetect
    3. multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="XP 2300" /3GB /USERVA=2300 /fastdetect
    4. multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="XP 2500" /3GB /USERVA=2500 /fastdetect
    5. multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="XP 2800" /3GB /USERVA=2800 /fastdetect
    Always copy and edit the last line of your Boot.ini file. It may be different from my last line. Using my line may make your system unable to boot.
    Line 1 is the original last line in my boot.ini file. As the first line in this group, it will be the default line if one does not make a different selection during the boot process. This is my escape hatch.
    Line 2 is modified to boot in the 3GB mode which allows 3GB of address space to the application and 1GB to the windows kernel.
    Line 3 provides 2.3GB of address space to the application and 1.7GB to the Windows kernel.
    I have all of these combinations available to test different hardware and drivers. You should not need to have all of these lines in your boot.ini file.
    Use what works. You have to allow enough space for the Windows kernel to run.
    Once you are finished modifying the boot.ini file, please protect it by changing it to read only.
    Microsoft has identified a problem for systems with multiple SCSI controllers.

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    Member KellyR's Avatar
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    Default Re: The 3/Gig Switch! Is this safe to use!

    We have used the 3gb switch here for around 1 1/2 years and have had no problems with it at all. In fact it has helped us out. We use to get the error message that we had used 80% of allotted memory and with the 3GB switch we have not seen that message for some time now.

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