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Thread: Ubuntu 64bit doesn't recognise all RAM

  1. #1
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    Sep 2012
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    Ubuntu 64bit doesn't recognise all RAM

    Hello,

    I recently bought a new 2x4GB kit of RAM for my Toshiba M750 laptop (originally a 2x2GB kit of RAM) running Ubuntu Server 12.10. However, when I reinstalled from 32bit to 64bit, Ubuntu says I only have 3895MB of RAM instead of around 8000MB.

    So I looked around the internet for a bit and I found you could see the installed amount of RAM in the BIOS. When I checked it said I had 8192MB. To make sure my computer supported that much RAM I contacted Toshiba and they said it could.

    On the internet I also found memtest86+. So I decided to run it and I got to Test 7 (Pass 44%) and I started getting millions of errors (About 7 million as I am writing this).

    Does anyone know why this is the case and possibly how to fix it?

    Thanks,

    JamesStewy
    Last edited by JamesStewy; January 3rd, 2013 at 12:31 AM. Reason: Better explains my situation

  2. #2
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    Re: Ubuntu 64bit doesn't recognise all RAM

    Quote Originally Posted by JamesStewy View Post
    Hello,

    I recently bought 4GB more RAM for my Toshiba M750 laptop (originally 4GB of RAM) running Ubuntu Server 12.10. However, when I reinstalled from 32bit to 64bit, Ubuntu says I only have 3895MB of RAM instead of around 8000MB.

    So I looked around the internet for a bit and I found you could see the installed amount of RAM in the BIOS. When I checked it said I had 8192MB. To make sure my computer supported that much RAM I contacted Toshiba and they said it could.
    When recognized by the BIOS, the RAM should be recognized by Ubuntu (64-bit version)

    On the internet I also found memtest86+. So I decided to run it and I got to Test 7 (Pass 44%) and I started getting millions of errors (About 7 million as I am writing this).

    Does anyone know why this is the case and possibly how to fix it?

    Thanks,

    JamesStewy
    According to my experience, when memtest complains, the RAM is bad. Or if you are lucky, there is a bad connection. If you wiggle the RAM cards a little, maybe they will connect better. Try that and run memtest again. If still bad, take out one RAM card each time to identify which one is bad and ask for it to be replaced.

  3. #3
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    Re: Ubuntu 64bit doesn't recognise all RAM

    Hello,

    Thanks for your help.

    I will try that now.

    JamesStewy

  4. #4
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    Re: Ubuntu 64bit doesn't recognise all RAM

    You are on a laptop. Chances are that the graphics card on your laptop uses some of the system memory and that is why not all 4GB is showing up.

    I've got 8GB RAM on my laptop but 512mb is used by the GPU so I only get 7.5GB of usable system memory.

  5. #5
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    Ubuntu 12.04 Precise Pangolin

    Re: Ubuntu 64bit doesn't recognise all RAM

    Quote Originally Posted by MrKrinkin View Post
    You are on a laptop. Chances are that the graphics card on your laptop uses some of the system memory and that is why not all 4GB is showing up.

    I've got 8GB RAM on my laptop but 512mb is used by the GPU so I only get 7.5GB of usable system memory.
    It is very unlikely that the graphics card uses half the RAM, since the OP upgraded from 4 GB to 8 GB of RAM.

    I recently bought 4GB more RAM for my Toshiba M750 laptop (originally 4GB of RAM) running Ubuntu Server 12.10. However, when I reinstalled from 32bit to 64bit, Ubuntu says I only have 3895MB of RAM instead of around 8000MB.

  6. #6
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    Re: Ubuntu 64bit doesn't recognise all RAM

    Hi MrKrinkin,

    Thanks for your reply.

    I fear I haven't explained myself correctly. I have 8gb of RAM installed in the computer but Ubuntu 64bit tells me I have around 4gb which is the amount I had before I bought some more.

    Sudodus, I did as you recommended and ran memtest86+ on both sticks of RAM individually and they both started giving errors at a very specific time in the test. As far as I could work out, both sticks of RAM started giving errors at the start very start of Test #7.

    Is there something worng with memtest86+? If it is right then both of my brand new sticks of RAM are faulty but the computer still runs fine? This doesn't make sense.

    EDIT: I did some research on Test #7 specifically and it turns out to be an issue. In places I read claims that the memtest86+ on the Ubuntu 12.10 64 bit install CD (the one I use) is faulty and other places that it is a test which cheaper/slower RAM will almost certainly fail. Could this be why I am getting strange results?
    Last edited by JamesStewy; January 2nd, 2013 at 11:06 AM. Reason: Research into Issue

  7. #7
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    Re: Ubuntu 64bit doesn't recognise all RAM

    You have two sticks of bad or wrong ram for you laptop.

    Do a search for ram for your laptop model number with Google.

  8. #8
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    Re: Ubuntu 64bit doesn't recognise all RAM

    But if they were two sticks of bad RAM, then why would Ubuntu install and work perfectly?

  9. #9
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    Re: Ubuntu 64bit doesn't recognise all RAM

    The bios is what tells the operating system how much ram is available.

    How much ram does your bios show?

  10. #10
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    Re: Ubuntu 64bit doesn't recognise all RAM

    Quote Originally Posted by JamesStewy View Post
    But if they were two sticks of bad RAM, then why would Ubuntu install and work perfectly?
    post output of

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