Windows 8 and 8.1 Forums

Only 3GB of RAM is Usable Out of 4GB (64-Bit Windows 8)

  1. #1

    Posts : 23
    Windows 8.1 Core X64

    Only 3GB of RAM is Usable Out of 4GB (64-Bit Windows 8)


    I have been refurbishing an old computer lately and have almost finished it

    But I have hit a problem with the RAM

    I can only use 3GB out of the 4GB I have installed

    The computer is manufactured by HP though the motherboard was made by ASUS

    This is the motherboard model - ASUS PTGD1-LA

    HP have a different name for it - Puffer UL8E

    The processor I have is an Intel Pentium 4 640 which is a 64 bit processor

    And like I said in the title I have 64 bit windows 8 installed

    Can someone please explain to me why it's only picking up 3.12 GB of RAM

    Computers Specs
    Intel Pentium 4 640 (3.2 GHz)
    RAM: 4GB DDR1 RAM (4X1) 400MHZ
    Seagate barracuda 7200.7 (200GB 7200RPM)
    ATI Radeon HD 5450 (Low Profile Bracket) PCI-E

      My System SpecsSystem Spec

  2. #2

    Is the 3.12 the "useable" RAM? If that is the case that is normal. Whether 32 bit or 64 bit OS, you will have something less than the 4GB of RAM useable as some is reserved for system, video, etc. My old system, which was Win 7 64 bit, had 4GB of RAM (later upgraded) and it had 3.24 GB of RAM available out of the 4GB (actually the same as when I had Vista 32 bit installed).
      My System SpecsSystem Spec

  3. #3

    Posts : 23
    Windows 8.1 Core X64

    Well i'm not 100% sure if this is wrong but I've got 2 laptops here one with 4GB of RAM and the other with 6GB of RAM and they are able to utilize all there ram and they both run on 64 bit OS so I can't understand why my PC can only use 3.12GB out of 4GB
      My System SpecsSystem Spec

  4. #4

    Orbiting the Moon
    Posts : 2,975
    Windows 10 x64

    It seems you hit some major hardware address space reservation.

    The model is pretty old and was initially not designed for 64bit (let alone tested).

    The fact that it's 64bit capable is a great thing.

    What do other OSes say about this?
    Does for instance Win7 x64 report another RAM size... or try a Linux Live CD in 64bit and see if you see different amount.
    Otherwise it's normal and you'll have to live with it, at least what concerns Win8.
      My System SpecsSystem Spec

  5. #5

    Orbiting the Moon
    Posts : 2,975
    Windows 10 x64

    One of my HP laptops can have up to 16GB RAM installed.
    It runs with 8GB from factory and a 64bit Win8 installed.

    I see 7.8GB usable from 8GB and this is the first one in x64 above 4GB I personally see to suffer from this.
      My System SpecsSystem Spec

  6. #6

    Posts : 65
    Microsoft Windows 8 Pro with Media Center 64-bit

    This is why I am now buying a new pc after upgrading the old one to 8 64bit.

    Although it runs 8 pretty darn good I still have only 2.95gb available which, I think is the same as I would have had in 32bit.

    Apparently it is because my old motherboard is not capable of remapping the memory to best advantage.

    That's what I been told anyway.
      My System SpecsSystem Spec

  7. #7

    Posts : 23
    Windows 8.1 Core X64

    Ahh i see. I have tried Windows 7 64 bit and i only get 3.2GB of ram out of 4GB. I will need to try a live cd of Ubuntu to see if that picks up any extra RAM and then ill reinstall Windows 7 or 8 (Not decided yet) to see if it will make a difference

    Thanks for your help guys
      My System SpecsSystem Spec

  8. #8

    Tropical Island Pair a Dice
    Posts : 3,030
    Windows 8.1 Pro x64/ Windows 7 Ult x64

    What does Control Panel > System, 'Installed memory (RAM)' say?

    Then check Resource Monitor, >Start Page, type 'resmon' press 'Enter', Memory tab.
    The bar graph shows what's being used and the list below is a re-cap.
    I have 8GB and it says:

    Available 6655 MB
    Cached 2654 MB
    Total 8152 MB
    Installed 8192 MB
    Last edited by Dave76; 14 Feb 2013 at 02:24.
      My System SpecsSystem Spec

  9. #9

    Posts : 7
    win 7 8 10

    Old thread but someone else may need this info:

    I had the same problem, and unchecked the max memory box in msconfig which returned the full 4gb to windows.

    Start, run, msconfig, boot, advanced options, uncheck maximum memory
      My System SpecsSystem Spec

Only 3GB of RAM is Usable Out of 4GB (64-Bit Windows 8)
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