GX280 upgrade to 4GB Ram - XP pro - shows 2.99 GB

For Enterprise

For Enterprise
Technology, Solutions & Services to meet your Business Needs

GX280 upgrade to 4GB Ram - XP pro - shows 2.99 GB

  • Hi,
    I wanted to upgrade a GX280 from 2GB to 4GB.
    Dell documentation indicates a maximum of 4GB for the GX280.
    Purchased the appropriate RAM directly from Dell.
    - BIOS recognizes 4GB.
    - The GX280 RAM indicators (LEDs) all show green.
     
    Windows XP Professional is indicating 2.99GB RAM installed.
    What would cause a "loss" of 1GB available memory?
    I understand some loss due to allocation but a whole GB seems like way too much.
    Ideas or Suggestions?
     
    Thanks
     
  • Install the Windows XP x64 in your computer if its CPU allows it (EM64T or EMT64).

    By the way, for each proccess the Windows 32-bits maps 2Gb of virtual RAM to system kernel and 2Gb of virtual memory to process. You can increase the amount of virtual memory mapped to applications to 3Gb (and reduce to 1Gb for system kernel) adding the /3GB to boot.ini.

    BEFORE:

    [boot loader]
    timeout=10
    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

    AFTER:

    [boot loader]
    timeout=10
    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

  • Thanks for the prompt response; unfortunately I cannot install WinXP x64.

    Three questions:

    1) Will changes to the boot.ini work on XP as well (2K is indicated the example)?
     
    The intended applications are doing some intense number crunching and calculations.
     
    2) What is the best "split" to enable XP to utilize the max amount of RAM for calculations?
     
    BTW - Dell support said to return the 2x1GB chips and replace with 2x512MB.
     
    3) Which config will provide fastest processing?
    - Dell solution or changing boot.ini
     
    Thanks,
     
    - J.
  • 1) Yes, but it has incompatibility issues with XP SP1. Please read this:

    http://support.microsoft.com/default.aspx?scid=kb%3Ben-us%3B328269

    2) I think 2x1Gb may reduce the latency time to access the memory in a dual-channel configuration, and the 2x1Gb + 2x512Mb configuration is better ($$$) than 4x1Gb if you will not install WinXP x64.

    3) The change in boot.ini is not a solution. It allows each process to access up to 3Gb of VIRTUAL MEMORY only, but it will not allow the windows to use 4Gb of PHYSICAL MEMORY. Please read this:

    http://www.microsoft.com/whdc/system/platform/server/PAE/PAEmem.mspx

  • Interesting reading - the incompatabilty was addressed with SP2 so the boot.ini change would likely function without any issues.

    Unfortunately I cannot go to XP x64 - No support for the applications the system is intended to run.

    It appears that I will have to downgrade the memory to 2x1GB and 2x512MB.

    It makes me wonder....

    Hmmm, will the OptiPlex GX620 that I just bought from Dell (with 4GB RAM) have the same issue? If yes, why would they enable it as an option?

    - J.

  • Any 32-bits windows have this issue, and 4Gb of RAM is a good option if you want to run Win XP x64.
     
    The Windows x64 is a problem only for 16-bits applications. When a Pentium with EMT64 or a Athlon 64 is in 32-bits mode, it can run 16-bits application. When it is in 64-bits mode, it can run 32-bits applications, but it cannot run 16-bits applications. 
     
    By the way, a 16-bits application cannot use more than 64Mb of RAM...
     
  • Sorry this is such a late addition to the thread, but I haven't been on the forums in awhile.

    Contrary to the Dell documentation, the GX280 can not address more than 3gb of RAM. There is no OS you can install that will get around this. You can install 2 1gb sticks and 2 512mb sticks for a total of 3gb.