Only 4gb of 6gb RAM listed as "Usable"

I am having problems with a build I completed about a month ago. I have 6gb of Mushkin RAM in a Gigabyte UD3R mobo. However, the computer lists only 4gb as "Usable." The problem didn't arise until I recently reinstalled Windows 7 for unrelated reasons. Before reinstalling all 6gb were recognized as usable. I am 100% positive I have the 64-bit version installed.

Any ideas? I think the sticks are all good, since they were working fine for the first month (I'm hoping... because it's too late for returns). I checked to make sure they are all still seated properly. I have not done any overclocking on this machine, but I read on other forums that improper voltages might cause this problem?

Thanks for any help,

Let me know if any other info would be helpful.



Running a full version of Windows 7 home premium. Intel i7 950.
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  1. Welcome to Tom's Forums! :)

    Do you have any partitions and/or bootable HDD/SSD with 32-bit OS installed.

    1. Load Optimized {you may also elect to Clear CMOS; shutdown}
    2. Verify Advance Boot Options {MSCONFIG}

    Please post the following:

    My assumption is that the 'missing' 2GB is H/W reserved. Also,when you 're-installed' the OS did you by chance reinstall the CPU??

    Furhter, I assume the RAM is properly install AND seated correctly in the DIMM slots DDR3_1/3/5

    Next, if both the Resource Monitor and/or CPUz only show 4GB vs 6GB you 'may' have a bad stick.

    If this is the case {or you want to test} then run Memtest to check if you have a bad stick D/L and create a bootable CD/DVD {ISO/zip} -
  2. Thanks for your reply,

    I have no partitions and/or bootable HDD/SSD with 32-bit OS installed.

    1. Loaded Optimized
    2. Verified Advance Boot Options - They are the same as your pic

    Resource Monitor

    It looks like all 6GB are accounted for according to Resource Monitor. 2GB are on hardware reserve. So I assume those 2 GB will be used if needed?

    After my original post, I had upgraded from Home Premium to Academic Professional. Take a look at the resource manager when I had Home Premium installed:

    Just kind of interesting I guess.

    RAM installed and seated correctly, and in the proper slots

    Resource Monitor and CPUz both show 6GB installed.

    I'm going to run Memtest just to make sure.
  3. The reinstallation corrected the problem! It is NOT normal to have 2GB of 6GB reserved in a 64-bit; it IS normal if your prior OS was 32-bit.

    Running Memtest won't hurt a thing.

    Good Luck! :)
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