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Problem RAM half used (single channel memory mode)

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  • Problem RAM half used (single channel memory mode)

    Hi, I was using asrock 970 extreme4 bios version 2.00 with 8gb fully detected by windows 7 x64 ultimate

    I just bought another pair Gskill 4gb 1600 cl9 (trying to match as much the ones i already have)
    When I check windows says 16gb (7.98 usable)

    - I noticed bios says single channel memory mode
    - I checked the msconfig boot section memory limit was off
    - Updated bios to 2.60
    - I have tried different ram slots (always using same color slot for same pair of ram)

    BIOS keep saying single channel memory mode so I remove the new ram, but now windows says: 8gb (3.96 usable)

    Some sites talk about activating "memory remap" in bios, which this asrock bios doesn't have.
    What is IOMMU use for? I can't find no solution. Please, any idea?

  • #2
    Re: Problem RAM half used (single channel memory mode)

    Originally posted by trozos View Post
    Hi, I was using asrock 970 extreme4 bios version 2.00 with 8gb fully detected by windows 7 x64 ultimate

    I just bought another pair Gskill 4gb 1600 cl9 (trying to match as much the ones i already have)
    When I check windows says 16gb (7.98 usable)

    - I noticed bios says single channel memory mode
    - I checked the msconfig boot section memory limit was off
    - Updated bios to 2.60
    - I have tried different ram slots (always using same color slot for same pair of ram)

    BIOS keep saying single channel memory mode so I remove the new ram, but now windows says: 8gb (3.96 usable)

    Some sites talk about activating "memory remap" in bios, which this asrock bios doesn't have.
    What is IOMMU use for? I can't find no solution. Please, any idea?
    Mixing different models of memory and having them match on the technical things that matter (capacity of the memory chips, layout of the chips (rank), single or dual sided mounting of the chips, etc) without knowing the details will be pure luck. If they don't match the results will be strange, as you have seen. Matching the speed (1600) and latency (CL 9) does not matter much at all compared to the other factors I mentioned above.

    Any time you change the memory (add, remove, or just move it) on a board, you should clear the BIOS/CMOS, and let the memory start up with all Auto memory settings in the BIOS. You should try this now with your new memory, and if you are lucky it might work fine, but I cannot guarantee that. You also need to clear the BIOS just to get your old memory working correctly, when it is used by itself.

    Usually when different models of memory are used together, and are incompatible with each other, or the system's memory controller, the memory that can be used will run it single channel mode.

    Have you tried using the new memory only in the board, and does it work by itself?

    An IOMMU is a memory mapping unit that translates a virtual address into a physical memory address. Clearing the BIOS/CMOS should clear any IOMMU tables in use, which is essential when changing a system's memory in any way. If you have an IOMMU option in your BIOS, what is its description?

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    • #3
      Re: Problem RAM half used (single channel memory mode)

      thanks parsec,

      IOMMU is disabled, i was just asking..
      when you say clear the bios/cmos, is not the same as restore the bios to default configuration, right? do i have to press some physical button in the motherboard?

      as soon as i get home i will check the new ram alone, but i'm nearly sure it will say 8gb installed 4gb available

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      • #4
        Re: Problem RAM half used (single channel memory mode)

        I've clear CMOS.. (I know because BIOS settings go back to default)

        I plugged the new ram pair alone in A1, B1 also A2, B2..

        and the old pair alone..

        all results = single channel memory mode

        Please, what could be happening?

        Comment


        • #5
          Re: Problem RAM half used (single channel memory mode)

          Hi parsec, thanks for you answer.

          Having checked everything, finally I took the pc to my nearest store.

          The final answer is: my Power Supply wasn't enough

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