Recognises 4gb ram, only uses 2.87 though

Hello all,
I have a problem with my RAM memory. I am trying to get geared up for BF3 and I upped my comp a little bit.

Windows Enterprise 64 bit
ATI Radeon 3870 x2
Intel Pentium Dual CPU E2160 @ 1.80 GHz
Asus P5LD2 Mother board
4gb RAM installed and recognised by Bios and Windows, but only 2.87 are being marked as usable by both

How can I fix this little ram problem, and get windows to use all 4gb of it?

I am not the most techiest person, so please keep it somewhat simple.
Thanks in advance,

forgot to add:
Motherboard allows max of 4gb ram
I installed 4gb kingston DDR2 Ram 533mhz
6 answers Last reply
More about recognises though
  1. I doubt you will be able to run Battlefield 3 at even the lowest possible settings and get playable framerates with that setup. Your cpu is well below minimum requirements and your gpu is right at the minimum.
  2. Sounds like a physical limitation of the motherboard, i once had a workstation motherboard with a similar issue. It supported 4 gigs but only showed 2.9 gigs usable with x64 bit. I later found out that it was the motherboard that had a physical limitation not the operating system.

    Only way to fix this is to get a newer motherboard or if your bios supports it there should be an option in there.

    This is the thread i got my information from my workstation i was building.

    If your too lazy to read through it heres the main part:


    I doubt you'll ever see this but just in case...

    I have the same problem. It is NOT related to the OS, since I have tried Linux, Win XP and Win 2003 Enterprise (which has an 8gb limit).

    I called HP and after 45 minutes I found out this is a known archiectural limit. HP emailed me the following.

    I have an additional graphics card, and a RAID controller in the machine. HP suggest I take them out, and install Win 2003 64 bit to see if the problem goes away. Marvellous...

    Hope this helps (explain it at least)


    Title: Personal Workstations - Total Memory Size Reported Incorrectly in Computers Equipped With 4GB Memory

    Total Memory Size Reported Incorrectly in Computers Equipped With 4GB Memory
    Symptomatic Description:
    Total Memory Size Reported Incorrectly in Computers Equipped With 4GB Memory

    Root Cause and Technical Description

    The Operating System reported the memory size incorrectly in Workstaion equipped with 4GB of Memory Modules. However, the size of the memory modules are reported correctly in the F10 Setup and POST. Due to architecture reasons not all of the physical memory will be available in systems equipped with 4096 MB of RAM. This issue is not specific to HP workstations. Any current system capable of supporting 4 Gigabytes of RAM will show this issue. For example, the following video controllers report the different memory size in W8000 with 4GM Memory :
    - Nvidia Quadro4 900 XGL : 3696 MB
    - ATI FireGL 8800 : 3440 MB
    - ATI Quadro2 Pro : 3696 MB
    - Matrox G450 Dual Head : 3888 MB

    This issue can occur on any computer with 4GB memory.

    To get better performance many devices use Memory Mapped I/O (MMIO) to transfer data between system memory and the device. Typical devices are graphics adapters, network interface cards, SCSI cards, and IEEE 1394 devices.

    To do MMIO a device will reserve a block of memory addresses. These addresses reside near the top of the addressable memory space. The MMIO range required for storage and I/O devices is usually small; somewhere around 1 MB each is typical. It can be much larger for devices like caching RAID cards.

    The MMIO address requirements of graphics adapters are usually much higher. This larger MMIO address requirement is needed to achieve the high performance required of workstation class graphics. (This is also true of high-end consumer/game graphics devices.) It is standard practice for a graphics device to reserve a MMIO area equivalent to the size of the frame buffer so that 1:1 memory accesses can be performed.
    Some current graphics adapters require twice the frame buffer. It is also common to see a few more megabytes of address space reserved in addition to the frame buffer for other uses. The AGP aperture memory is also an MMIO region. The AGP aperture is configurable in the BIOS setup and is typically set to 64 MB.

    Current systems have 32 address lines. This means that they can address
    4,294,967,296 bits or 4 GB. When 4GB of physical memory is installed, these reserved address ranges actually reside in physical memory, making that memory unavailable for the operating system.

    There is another constraint that further reduces the available memory.
    The PCI 2.2 specification dictates that root PCI bus must be allocated one block of MMIO addresses. This block of addresses is subdivided into the regions needed for each device on that PCI bus. And each of those device MMIO regions must be aligned on addresses that are multiples of the size of the region. For example, a 256MB region must be aligned on addresses that are multiples of 256MB (10000000h).

    The system BIOS itself needs an MMIO range that is always fixed at the top very top of memory. The BIOS is typically 512 KB so it reserves FFF80000h to FFFFFFFFh. This range of addresses reserved by the BIOS cannot be moved.

    In practice, altogether this means that the MMIO ranges at the top of the memory addresses become fragmented and more memory than expected is consumed by MMIO. Resolution

    This issue is not specific to HP workstations and the system is working as designed.

    See HP White Paper for clarification:
  3. oh gee, new motherboard and cpu then.......gonna be expensive......thought i could get away cheaply since i paid nothing for the new ram and graphics card.

    what type of motherboard would still support DDR2 ram and a decent processor?
    i am not worried about the graphics card cuz its new.
    any ideas?
  4. thanks. so to get ready for bf3 all i would need is better motherboard and cpu right?
    as far as i know my graphic card very good is good enough for bf3, and my ram would be over the minimal requirements.

    with the setup i have atm i can run Crysis 2 at good graphics with no lag/glitch whatsoever, so i am not too concerend about that

    your thoughts/input?
    thanks again guys. great help
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