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Can Vista Handle 4 Gb RAM?

Discussion in 'Windows Vista' started by AustinM, Feb 14, 2007.

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  1. AustinM

    AustinM Thread Starter

    Feb 7, 2004
    Computer specs:
    Asus P5W DH motherboard
    Intel Core2 Duo 2.4GHz
    Vista Home Premium
    4x1Gb Kingston HyperX DDR2-800 ram
    2x Asus 7600GT 256MB video cards
    650w Seasonic psu
    150GB WD Raptor HDD

    The mobo is configured for dual channel memory. I first had 2x1 Gb sticks installed, and the system saw and reported 2.00 Gb memory. When I installed the second set of 1Gb sticks (for a total of 4x1Gb), the system now reported 2688 Mb total memory.

    The bios lists 4096 Mb memory, but says that 1408 Mb is appropriated and 2688 is available. Is there any way to reconfigure and/or release the ~1.4 Gb of apopropriated memory, to get total available physical memory closer to 4 Gb?

    I've found a few places that reference adding a /PAE switch to boot.ini. After some research, Vista doesn't use boot.ini, it uses bcdedit.exe to modify the BCD store. I downloaded a couple programs to modify the BCD store, turned PAE on, but nothing different. PAE stands for Physical Address Extension, and it should send a 64 bit addy as two 32 bit addys...

    I'm fairly certain that the problem is in Vista. The bios will accurately detect 4096 Mb physical memory, but then I think that Vista is allocating upper memory addresses to other system memory, like what's on my video cards, etc. I've updated the most recent bios for my mobo (from 2/9/07), and that changed nothing.

    Still looking for a fix... Am I missing something?
  2. uhaligani

    uhaligani Guest

    Apr 6, 2006
    If your video adapter has 512MB of RAM or 2 x 256, like yours), your maximum memory is going to at most be 3.5GB, because Vista has to use 512MB of that address space to address your video memory. It’ll actually be lower than the 3.5GB because there are other hardware resources that need address space, too. So, it never hurts to fill your computer with 4GB of RAM–you’ll definitely get the max, but you won’t be able to address it all. You probably won’t be able to address much more than 3GB, and you might not be able to address more than 2GB.
    I understand the 64 bit Vista can show you the full amount.
  3. TRS-80 vet

    TRS-80 vet Account Closed

    Jun 17, 2005
    Might be enough.

    If you turn the unit on, all bets are off.:D Tasman shows 70 processes before you touch a key.:eek:
  4. TechB


    Jul 23, 2006
    You have run into a limit that exists in all 32 bit versions of Windows. There is a 4 GB address space available to a 32 bit OS. Some of this address space is needed to memory map peripherals. The motherboard does this before Windows loads and this determines how much RAM Windows reports. Some motherboards have settings in the BIOS that can change this, most don't. The fix is to run a 64 bit OS. Even then some motherboards will still have this limitation.
  5. AustinM

    AustinM Thread Starter

    Feb 7, 2004
    TechB - Correct.

    I've modified my bcd store to include the /PAE switch - hoping that would add another 4 bits onto the address, but no luck. Windows still reports 2688Mb.

    My mobo bios does have a memory remapping enable/disable feature - but it's only for an x64 system. If it's enabled on my x86 system, Windows reports 2Gb ram.
  6. jimboy


    Mar 30, 2005

    Yup, just like mine. I got 4 gigs and in windows XP or vista I only got 3.5gb. But in my bios, unlike you, it stills registers 3.5gb hmm...?? :confused:

    Anyways, one time my bios count 4gb memory and I don't remember what I did lolz :D

    Maybe I should consult this in this forums :p (y) :D
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