total memory available is only 3.3GB with 4GB physical memory under windows 7 64 bit

Discussion in 'Windows 64bit' started by someone, Nov 29, 2009.

  1. someone

    someone Guest

    I had 4GB physical memoryon the PC. With Windows vista 32 bit,
    available memory is shown as 3.3GB. I asked and was told that only
    under 64 bit windows, will the available memory be 4GB. When I
    upgraded to windows 7, I chosed 64 bit, but the available memory shown
    in the system is still 3.3 GB.

    Why is this and is there a way to make the full 4GB available?

    It's possible that my video card is using RAM instead of its own RAM.
    If I install a video card with its own RAM, will the full 4GB be

    someone, Nov 29, 2009
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  2. Little has changed in this respect in Windows 7.

    Starting with Vista SP1, Windows now 'reports all of the installed RAM',
    instead of only what is available to the OS.

    However, nothing has changed as far as what is available to the OS. As
    others have stated, with 4GB RAM installed, around 2.5 to 3.6GB will be
    available, depending on the system.

    Hope this helps.

    And read the Microsoft KB @
    Bobby Johnson, Nov 29, 2009
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  3. someone

    Dennis Pack Guest

    You need to verify that the ram remapping above 4GB is enabled in
    the bios to read the full system ram. Have a great day.

    Dennis Pack
    Win-7 Enterprise x64, Win-7 Professional x64.

    __________ Information from ESET NOD32 Antivirus, version of virus signature database 4647 (20091129) __________

    The message was checked by ESET NOD32 Antivirus.
    Dennis Pack, Nov 29, 2009
  4. 32-bit Windows can address a maximum of 4GB. Graphics memory and system
    BIOSes are included in the 4GB, so available addresses for RAM are less:
    usually from about 3.5GB down to 2.7GB or so if a very large graphics
    card is fitted.

    64-bit Windows can address a much larger space, so provided the BIOS
    allows the hardware addresses to be mapped above 4GB the full 4GB of RAM
    - or more if fitted - can be addressed and used.

    If you use onboard graphics which uses system RAM whatever is allocated
    to graphics will not be available to applications. For 32-bit Windows it
    would make no difference if 4GB was fitted, but would if there was less.
    For 64-bit Windows separate physical graphics RAM is an advantage.
    Dominic Payer, Nov 29, 2009

  5. Three points here:

    1. All 32-bit client versions of Windows (not just Vista/XP/7) have a
    4GB address space (64-bit versions can use much more). That's the
    theoretical upper limit beyond which you can not go.

    But you can't use the entire 4GB of address space. Even though you
    have a 4GB address space, you can only use *around* 3.1GB of RAM.
    That's because some of that space is used by hardware and is not
    available to the operating system and applications. The amount you can
    use varies, depending on what hardware you have installed, but can
    range from as little as 2GB to as much as 3.5GB. It's usually around

    Note that the hardware is using the address *space*, not the actual
    RAM itself. If you have a greater amount of RAM, the rest of the RAM
    goes unused because there is no address space to map it to.

    2. In SP1 and SP2, Vista now reports all the RAM that's installed, not
    just what you can access. I think that's a very poor thing Microsoft
    did, since it misleads people. Nevertheless, you need to tell us what
    level of Vista it was. Was SP1 or SP2 installed? If so, what I said
    above doesn't matter and all 4GB should be reported.

    3. So if it was SP1 or SP2, and 3.3GB was reported, then that was all
    there was. You presumably have on-motherboard video support rather
    than a separate video card, and the rest of the RAM was used for that.
    But .7GB seems like a very strange number for on-motherboard video

    Your video card doesn't use System RAM. But again, if you have
    on-motherboard video support instead of a video card, that's
    presumably where the rest of RAM is being used, and whether Windows is
    32-bit or 64-bit doesn't matter. (But again the amount seems very

    If it weren't for that .7GB being so strange, I would say that was
    almost definitely your issue and yes, installing a video card would
    solve the problem. But with that strange number, I'm not sure.
    Ken Blake, MVP, Nov 29, 2009
  6. someone

    Jeff Gaines Guest

    On 29/11/2009 in message <> Ken
    The OP said he had installed Win7-64 though.
    Jeff Gaines, Nov 29, 2009
  7. someone

    wayneP Guest

    The original post is confusing. 64 bit isn't a regular upgrade from 32 bit.
    It would require a custom or clean install. It appears that the OP might
    have just upgraded 32 bit Vista to 32 bit Windows 7 and thus the same amount
    of ram is being reported.

    wayneP, Nov 30, 2009
  8. Like others said, the OP most likely needs to remap memory above the 4GB
    barrier (in the BIOS).

    John John - MVP, Nov 30, 2009
  9. someone

    wayneP Guest

    I thought recent mobos did memory remapping by default. I know there is no
    option in the BIOS of my A780GM-A Ultra to remap memory. With my recently
    installed Vista 64, there is an indication that there is 3.75 GB of memory
    (2x2 GB sticks) installed and 2.52 is available. The onboard video is using
    256 MB and I assume other system devices and/or processes account for the
    remainder of the difference between 3.75 and 2.52.


    wayneP, Nov 30, 2009
  10. If you have 4GB installed and if the onboard video is using 256MB then
    the remaining 3.75GB should be available to your x64 operating system.
    Where do you see that only 2.52GB is installed? I don't know what you
    are running on your computer but unless you are running very hungry
    applications I have a hard time believing that your processes are using
    1.25GB of RAM!

    This (lost RAM) is an addressing issue only, the hardware doesn't use
    the lost RAM nor does the operating system. The hardware reserves
    addresses at the top of the memory range just under the 4GB barrier so
    that it can communicate directly with the processor, in turn the
    reserved addresses are not available for the installed RAM so you cannot
    see or use all the RAM (on 32-bit Windows), the RAM is without addresses
    so it goes unused. The way around the problem is to remap the RAM
    without addresses above the 4GB barrier and to use a 64-bit or PAE
    capable operating system to access the memory above the 4GB barrier.

    John John - MVP, Nov 30, 2009
  11. Hello
    I have 64Bit Vista Ultiamte and 8Gb of RAM, the Operating System sees
    all of the RAM, when I was running 32bit Vista with 4Gb of RAM the most
    it could see was 2.25Gb due to the fact that I am running a pair of
    GPU's each with 512Mb of RAM.

    Michael John Ruff, Nov 30, 2009
  12. Not all machines do this automatic remapping, true that it is to be
    expected on newer machines but don't bet the farm that all machines do it.

    John John - MVP, Nov 30, 2009
  13. someone

    wayneP Guest

    I'm running Vista x64 Ultimate and under System Tools there is a System Info
    option. This isn't something I look at regularly but I did check it just
    after I rebuilt this machine with a tri-core Phenom II and installed x64.

    In there it shows Total Physical Memory and Available Physical Memory. This
    is where I saw 2.52 GB available memory (not 2,52 installed) before posting
    yesterday. This number changes and this AM it is showing 3.00 GB. The fact
    that it changes led me to believe that the number has something to do with
    what is running on the machine at the given time.

    wayneP, Dec 1, 2009
  14. someone

    Carlos Guest

    You are quite right, it depends on how many programs/processes are running.
    This little gadget:
    might help you understand your memory use, besides the cpu load on each core.
    It shows you the used, free and total memory.
    Carlos, Dec 1, 2009

  15. What you say is correct. Available physical memory is the difference
    between the total amount of RAM and what is in use at the time.

    If you typically have that much available memory, you have more RAM
    installed than you need--more than what you do with your computer can
    make effective use of.
    Ken Blake, MVP, Dec 1, 2009
  16. someone

    someone Guest

    See attached for phyical and available memory as reported by Win7.

    someone, Jan 12, 2010
  17. someone

    someone Guest

    Attachement doesn't seemt to show up in previous post.
    someone, Jan 12, 2010
  18. someone

    someone Guest

    Don't know why attachment still doesn't show up.

    Anyway, the following line is shown by win7 (Computer->Properties):

    Installed Memory (RAM): 4.00GB (3.25GB usable).

    Task Manager->Performance shows 3326MB as Total Physical memory.

    This is 64 bit win 7 for sure.

    Why only 3.25GB shown as usable? Under Vista 32 bit, it was the same.
    Only 3.2 GB was shown as usable. I thought upgrading to 64 bit (it
    was a clean install during "upgrading" of course) will help.
    someone, Jan 12, 2010
  19. Hello

    Very Strange I run Windows 7 64 bit and have 8Gb which all shows,
    running 2 Graphics cards with 512Mb each.

    All I can think is that the motherboard doesnt fully support 64 bit ?

    Michael John Ruff, Jan 12, 2010
  20. Something related to your motherboard. Could be a BIOS setting for
    Memory Remap or a number of other things. You would need to check with
    the manufacturer of your motherboard to find out the rest of the story.
    Bobby Johnson, Jan 12, 2010
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