Not all of my RAM is usable in Windows 7 64-bit

I recently upgraded to a 64-bit OS so that I could take advantage of all my RAM. I have 2x1GB and 2x 512MB, I also have an Nvidia 8600GTS with 512MB video ram. Under Windows XP Pro SP3 only 2.25G was ever available. As I understand it, only 4GB of memory is possible with a 32-bit system, and even that is not likely as memory addressing space is used up by video card RAM, and other devices to some extent.

So immagine my surprise when I buy and upgrade to Windows 7 64-bit, only to discover in my system properties "3 GB (2.25 GB usable)"

To address some of the common solutions or explanations I've read about and tried before posting:

My BIOS sees the 3 GB of RAM. My BIOS supports up to 4 GB of RAM.

I tested the memory, and none of it is faulty.

I even removed alternating pieces of RAM and tried using them individually, they were all recognized and worked.

Yes, I am sure I'm running a 64-bit OS.

There is no memory remapping setting in my BIOS.

I've tried running msconfig and going to the boot tab, then advanced, and making sure the max memory isn't being limited.

So, anyone know why my memory isn't able to be used under my 64-bit OS? How can I fix this?
6 answers Last reply
More about usable windows
  1. Possibly relevant system specs from System Information (I pruned a lot out)

    System Information report written at: 01/26/10 16:17:52
    System Name: FROSTWYRM
    [System Summary]

    Item Value
    OS Name Microsoft Windows 7 Professional
    Version 6.1.7600 Build 7600
    Other OS Description Not Available
    OS Manufacturer Microsoft Corporation
    System Name FROSTWYRM
    System Manufacturer Dell Inc.
    System Model Dimension 8400
    System Type x64-based PC
    Processor Intel(R) Pentium(R) 4 CPU 3.00GHz, 2992 Mhz, 1 Core(s), 2 Logical Processor(s)
    BIOS Version/Date Dell Inc. A05, 3/16/2005
    SMBIOS Version 2.3
    Windows Directory C:\Windows
    System Directory C:\Windows\system32
    Boot Device \Device\HarddiskVolume1
    Locale United States
    Hardware Abstraction Layer Version = "6.1.7600.16385"
    User Name Not Available
    Time Zone Pacific Standard Time
    Installed Physical Memory (RAM) 3.00 GB
    Total Physical Memory 2.25 GB
    Available Physical Memory 1.61 GB
    Total Virtual Memory 4.49 GB
    Available Virtual Memory 3.65 GB
    Page File Space 2.25 GB
    Page File C:\pagefile.sys

    [Hardware Resources]

    [Conflicts/Sharing]

    Resource Device
    I/O Port 0x00000000-0x00000CF7 PCI bus
    I/O Port 0x00000000-0x00000CF7 Direct memory access controller

    I/O Port 0x000003C0-0x000003DF Intel(R) 925X/XE PCI Express Root Port - 2585
    I/O Port 0x000003C0-0x000003DF NVIDIA GeForce 8600 GTS

    IRQ 21 Intel(R) 82801FB/FBM USB Universal Host Controller - 2658
    IRQ 21 Intel(R) 82801FB/FBM USB2 Enhanced Host Controller - 265C

    IRQ 23 SoundMAX Integrated Digital Audio
    IRQ 23 Intel(R) 82801FB/FBM USB Universal Host Controller - 265B

    IRQ 16 Intel(R) 925X/XE PCI Express Root Port - 2585
    IRQ 16 Intel(R) 82801FB/FBM PCI Express Root Port - 2660
    IRQ 16 NVIDIA GeForce 8600 GTS
    IRQ 16 Broadcom NetXtreme 57xx Gigabit Controller

    Memory Address 0xA0000-0xBFFFF Intel(R) 925X/XE PCI Express Root Port - 2585
    Memory Address 0xA0000-0xBFFFF PCI bus
    Memory Address 0xA0000-0xBFFFF NVIDIA GeForce 8600 GTS

    I/O Port 0x000003B0-0x000003BB Intel(R) 925X/XE PCI Express Root Port - 2585
    I/O Port 0x000003B0-0x000003BB NVIDIA GeForce 8600 GTS

    Memory Address 0xDC000000-0xDFEFFFFF Intel(R) 925X/XE PCI Express Root Port - 2585
    Memory Address 0xDC000000-0xDFEFFFFF NVIDIA GeForce 8600 GTS


    [Memory]

    Resource Device Status
    0xDC000000-0xDFEFFFFF Intel(R) 925X/XE PCI Express Root Port - 2585 OK
    0xDC000000-0xDFEFFFFF NVIDIA GeForce 8600 GTS OK
    0x90000000-0xBFFFFFFF Intel(R) 925X/XE PCI Express Root Port - 2585 OK
    0xA0000-0xBFFFF Intel(R) 925X/XE PCI Express Root Port - 2585 OK
    0xA0000-0xBFFFF PCI bus OK
    0xA0000-0xBFFFF NVIDIA GeForce 8600 GTS OK
    0xDBF00000-0xDBFFFFFF Intel(R) 82801FB/FBM PCI Express Root Port - 2660 OK
    0x8FF00000-0xDFFFFFFF PCI bus OK
    0xF0000000-0xFEBFFFFF PCI bus OK
    0xDBE00000-0xDBEFFFFF Intel(R) 82801FB/FBM PCI Express Root Port - 2662 OK
    0x0000-0x9FFFF System board OK
    0x100000-0xFFFFFF System board OK
    0x1000000-0x8FE8CBFF System board OK
    0xC0000-0xFFFFF System board OK
    0xFEC00000-0xFECFFFFF System board OK
    0xFEE00000-0xFEEFFFFF System board OK
    0xFED20000-0xFED9FFFF System board OK
    0xFFB00000-0xFFBFFFFF System board OK
    0xFFC00000-0xFFFFFFFF System board OK
    0xDE000000-0xDEFFFFFF NVIDIA GeForce 8600 GTS OK
    0xA0000000-0xBFFFFFFF NVIDIA GeForce 8600 GTS OK
    0xE0000000-0xEFFFFFFF Motherboard resources OK
    0xFEDA0000-0xFEDACFFF Motherboard resources OK
    0xDFFFFC00-0xDFFFFFFF Standard AHCI 1.0 Serial ATA Controller OK
    0xDFFFFA00-0xDFFFFBFF SoundMAX Integrated Digital Audio OK
    0xDFFFF900-0xDFFFF9FF SoundMAX Integrated Digital Audio OK
    0xDBFF0000-0xDBFFFFFF Broadcom NetXtreme 57xx Gigabit Controller OK
    0xDBDDF000-0xDBDDFFFF PCI Modem OK
    0xDBD00000-0xDBDFFFFF Intel(R) 82801 PCI Bridge - 244E OK
    0xFED00000-0xFED003FF High precision event timer OK
    0xFEBFFC00-0xFEBFFFFF Intel(R) 82801FB/FBM USB2 Enhanced Host Controller - 265C OK

    [Components]


    [Display]

    Item Value
    Name NVIDIA GeForce 8600 GTS
    PNP Device ID PCI\VEN_10DE&DEV_0400&SUBSYS_22891682&REV_A1\4&701F2C4&0&0008
    Adapter Type GeForce 8600 GTS, NVIDIA compatible
    Adapter Description NVIDIA GeForce 8600 GTS
    Adapter RAM 512.00 MB (536,870,912 bytes)
    Installed Drivers nvd3dumx.dll,nvwgf2umx.dll,nvwgf2umx.dll,nvd3dum,nvwgf2um,nvwgf2um
    Driver Version 8.16.11.9107
    INF File oem3.inf (Section003 section)
    Color Planes Not Available
    Color Table Entries 4294967296
    Resolution 1280 x 1024 x 60 hertz
    Bits/Pixel 32
    Memory Address 0xDE000000-0xDEFFFFFF
    Memory Address 0xA0000000-0xBFFFFFFF
    Memory Address 0xDC000000-0xDFEFFFFF
    I/O Port 0x0000DC80-0x0000DCFF
    IRQ Channel IRQ 16
    I/O Port 0x000003B0-0x000003BB
    I/O Port 0x000003C0-0x000003DF
    Memory Address 0xA0000-0xBFFFF
    Driver c:\windows\system32\drivers\nvlddmkm.sys (8.16.11.9107, 10.77 MB (11,293,928 bytes), 9/28/2009 12:12 AM)
  2. Find and run: msconfig.exe
    Go to the boot tab
    Click Advanced Options
    Make sure that the Maximum memory checkbox is not checked
  3. ekoostik said:
    Find and run: msconfig.exe
    Go to the boot tab
    Click Advanced Options
    Make sure that the Maximum memory checkbox is not checked


    "I've tried running msconfig and going to the boot tab, then advanced, and making sure the max memory isn't being limited. "
  4. My bad. By the time I got through scanning two pages of system specs I forgot some of what was in the first post. At least I didn't ask if you were sure you installed 64-bit!
  5. Im going out on a limb with this - I believe the max addressable space available to you is 4G. That means you will see the same available RAM regardless of a 32 bit or 64 bit OS. That is a fairly old system and 4G would have been almost unheard of back then.... I have seen others report something similar with older systems...

    I dont think its anything you are doing.

    Im fine if someone tells me Im wrong btw...??
  6. According to the following web site, "Although the BIOS will address 4GB of memory, only 3GB can be utilized by the system." http://www.edgetechcorp.com/memory/upgrade.asp?cid=21953

    This would explain why you see the exact same amount in XP SP3 32-bit, and Win7 64-bit. 32-bit shouldn't limit you until you get up to 4, but since you are seeing the same in both cases it makes sense that it is a hardware limitation.

    Your specs show you're running the A05 BIOS from 3/16/2005. Dell now has an A09 available from 8/14/2006 you could give a try and see if they upgraded board capabilities. http://support.dell.com/support/downloads/download.aspx?c=us&cs=19&l=en&s=dhs&releaseid=R129671&SystemID=DIM_PNT_P4_8400&servicetag=&os=WW1&osl=en&deviceid=308&devlib=0&typecnt=0&vercnt=10&catid=-1&impid=-1&formatcnt=1&libid=1&typeid=-1&dateid=-1&formatid=-1&fileid=172856
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