Help, total ram not being recognized!!!

Discussion in 'Mac Pro' started by hitman10, Feb 18, 2008.

  1. hitman10 macrumors newbie

    Joined:
    Feb 18, 2008
    #1
    Hi, I installed 2 x 2gb sticks of ram with the mac ram that was already installed in the computer. I checked to see if the computer recognized the ram and it did recognize it had 6gb installed.

    I went to check it again today and noticed that it stated that i had only 4gb installed. I went to check the memory set up in "about this mac" option and clicked memory and noticed it recognized the 4 dimm risers that had the memory installed but the 2gb dimms were stated at 1gb each.

    I uninstalled them and installed them again and checked it again where it stated 6gb of ram was installed. I thought i solved it but i just went to check it again and it is again stating i only have 4gb installed ( 4 dimm risers with 1gb installed).

    Any information would greatly be appreciated.
     
  2. TripleCore macrumors regular

    Joined:
    Oct 30, 2007
    #2
    If this is for a Mac Pro, while the factory install is Riser A: 1GB, Riser B: 1GB, if you add more ram, this changes. I am guessing this might be your problem. My machine is installed so that:

    Riser A: 1 GB 1 GB 2 GB 2 GB
    Riser B: 2 GB 2 GB

    where the first pair goes in slots 1 and 2 on A, second on slots 3 and 4 on A, third pair in slots 1 and 2 on B.

    Note that they are not symmetrically balanced across Riser A and B. Check your manual for more variations.

    Hope this helps.
     
  3. hitman10 thread starter macrumors newbie

    Joined:
    Feb 18, 2008
    #3
    Yes it is a mac pro. The configuration i have is

    Riser a: 1gb 1gb
    Riser b: 2Gb 2gb
     
  4. bigbird macrumors 6502

    Joined:
    Aug 17, 2007
    Location:
    Canada
    #4
    Flip your RAM around by putting the 2 GB sticks in riser A, slots 1 & 2, and the 1GB sticks in riser B, slots 1 & 2
     
  5. bigbird macrumors 6502

    Joined:
    Aug 17, 2007
    Location:
    Canada
    #5
    This doesn't look optimal. You aren't installing with matched pairs in upper and lower risers.
    I would put:
    Riser A: 2GB - 2GB - 1GB - 1GB
    Riser B: 2GB - 2GB - empty-empty

    That would give you 2 matched pairs in slots 1 & 2 of both risers. That's where the RAM is utilized first and fastest.
     
  6. hitman10 thread starter macrumors newbie

    Joined:
    Feb 18, 2008
    #6
    I tried placing the 2 GB sticks in riser A, slots 1 & 2, and the 1GB sticks in riser B, slots 1 & 2 when i first installed the ram and it did not recognize the 1gb sticks, but i will try it again and wait a few hours to see if will recognize this setup.
     
  7. bigbird macrumors 6502

    Joined:
    Aug 17, 2007
    Location:
    Canada
    #7
    With that config you wouldn't have matched pairs in slots 1 & 2 of both risers. Report back after you try the above suggested config.
     
  8. hitman10 thread starter macrumors newbie

    Joined:
    Feb 18, 2008
    #8
    Hi Guys, thanks for the info. I tried this setup and so far so good.

    Riser a: 1gb 1gb 2gb 2gb
    Riser B: nothing

    Will purchase another 2 x 2gb sticks in the near future
     

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