Can you limit the amount of usable RAM within a DIMM ?

Discussion in 'Hardware Components and Aftermarket Upgrades' started by miro_gt, Dec 30, 2012.

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  1. miro_gt

    miro_gt Notebook Deity

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    I may run into a specific situation where I need to free more PCI address space otherwise taken my RAM. So is it possible to program a DIMM stick to make it smaller ? ... i.e. 1GB DDR2 DIMM to show as 768MB stick in BIOS for instance ?

    thanks.
     
  2. rofler

    rofler Notebook Guru

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    Yes, I believe there is a way in Windows to set it. Go to:

    Start-->msconfig.exe-->Boot-->Advanced Options--->Maximum memory

    After selecting the check box, type in the amount of memory you desire; you can also change the number of CPU cores that can be used, as well. You will have to reboot thereafter to see the effects.
     
  3. miro_gt

    miro_gt Notebook Deity

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    not in Windows, I need to program that into the DIMM itself, I need it to show as smaller in BIOS.
     
  4. OtherSongs

    OtherSongs Notebook Evangelist

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    Why not tell us what you are trying to accomplish?

    Anyhow I've never seen anything like that, even in a desktop PC BIOS.

    Laptop PC BIOS are generally much more limited, with the options that you can set in the BIOS.
     
  5. whitrzac

    whitrzac The orange end is cold...

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    Typhoon burner, maybe...


    or buy 512mb sticks.
     
  6. Greg

    Greg Notebook Nobel Laureate

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    There isn't anything you are going to be able to do to increase available address space, at least not without buying smaller capacity RAM sticks.
     
  7. Megol

    Megol Notebook Evangelist

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    Shouldn't reprogramming the SPD EEPROM/Flash to 1/2 the capacity work?
    Of course just buying a smaller DIMM would be much easier.
     
  8. miro_gt

    miro_gt Notebook Deity

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    programming it for 1/2 isn't worth the trouble since I can just buy 512MB DIMM. The thing is that I'm going to add external graphics card to my laptop via docking station and it works with up to 2.5GB RAM installed but doesnt work with 3GB RAM or more, thus the problem is somewhere within that 512MB above 2.5GB address region.

    Now I run XP 32bit which reports ~2.9GB as usable RAM in Task Manager (I got 4GB RAM installer right now in both my T61 laptops), which is enough for 99% of the things I run, and I dont use page file. The most RAM in use I've seen is around 2.5GB when playing a heavy game. So if somehow I could use a "768MB DIMM" and a 2GB DIMM and that works out fine then I'll gain 256MB of RAM which will be worth having in this case, i.e. 2.75GB RAM total. XP itself can fit within 512MB RAM, and all the small utility programs at my start up are within 256MB, so that would leave a nice 2GB RAM window for a single program (game), which is the maximum standard memory window anyways.

    I was hoping somebody with Typhoon burner experience to share thoughts ...
     
  9. Duct Tape Dude

    Duct Tape Dude Duct Tape Dude

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    Are you absolutely sure it won't work with 3+2.5GB?

    Most 32-bit addressing issues just ignore a portion over 4GB. ie: a 12GB system will show just over 3GB useable. The OS will cut things off for you when it has a choice of graphics memory and system memory.

    What kind of docking station is this?

    Is it more than just a pcie extension?

    If you are only using the docking station for a pcie gpu, the OS won't know the difference anyway and treat it exactly as if you had inserted a graphics card on the pcie slot. I think you might be looking at the situation wrong.
     
  10. James D

    James D Notebook Prophet

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    thaiphoon burner can disable certain memory chips on stick... but I don't know how. It should be done if you know what memory chip is faulty and you don't want to RMA or throwing away whole stick.

    Just use Windows XP x64 or Windows 7
     
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