14GB upgrade only shows as 12GB

Discussion in 'Mac Pro' started by Julien, Oct 19, 2013.

  1. Julien macrumors G3

    Julien

    Joined:
    Jun 30, 2007
    Location:
    Atlanta
    #1
    My Mac Pro (3,1) came with 2GB and have upgraded in the past with 8GB for 10GB (no problem). I just bought a 4GB RAM set but it only shows as 12GB. I thought the RAM was defective and had it replaced but still have the same problem. I have it set up as follows. Riser A 2GB+2GB, 2GB+2GB: Riser B 2GB+2GB, 1GB+1GB. This follows the Mac Pro install chart.

    Is there a problem using 1GB (2) RAM on Riser B with 2GB RAM on Riser A (it worked fine with 10GB)? Is it not possible to show 14GB because of this?
     
  2. westrock2000 macrumors 6502

    Joined:
    Oct 18, 2013
    #2
    In "About This Mac", what does the graphical representation if the memory slots show? Does it match up to physical install?
     
  3. pastrychef macrumors 601

    pastrychef

    Joined:
    Sep 15, 2006
    Location:
    New York City, NY
    #3
    Those riser cards can be a bit temperamental. Try reinserting them a few times and try cleaning the contacts on the edge of the riser cards with a pencil eraser (remember to clean off debris left by the eraser).
     
  4. Julien thread starter macrumors G3

    Julien

    Joined:
    Jun 30, 2007
    Location:
    Atlanta
    #4
    No, it should be 2GB & 2GB in Riser B slots 1&2.
    [​IMG]

    I have swapped changed RAM on Riser B and checked/reinserted many times. I will try moving the new RAM to Riser A and see if it shows up 4GB instead of 2GB.
     
  5. NOTNlCE macrumors 6502a

    NOTNlCE

    Joined:
    Oct 11, 2013
    Location:
    DMV Area
    #5
    Had a similar problem a little while ago while mixing RAM speeds (something that's advised against, but whatever) - My solution was to mix the pairs up. The pairing on the '08s has a lot to do with how the RAM is recognized. I would move it into every configuration you can, even if it means swapping RAM on the risers. Also, check the dust around or on the risers, I had a small particle stuck on the connector and it was preventing any RAM from being recognized properly on that riser. A nice can of compressed air or a very gentle air compressor can take care of that. Good luck to you.
    -N
     
  6. netkas macrumors 65816

    Joined:
    Oct 2, 2007
    #6
    Have an issue with one of 2gb (config 1,1,1,1,2,2,2,2) planks being overheating and disabled by efi after reboot. So on cold(literally !) boot I have 12 gb, after some work and reboot - 10 gb.

    maybe ur's overheats too ?
     
  7. jaxhunter macrumors regular

    jaxhunter

    Joined:
    Dec 14, 2012
    Location:
    Arizona
    #7
    I once had a set of RAM sticks from Kingston that said 2GB Kit on the side of each stick; they were a matched pair of 1GB sticks that came as part of a 2GB kit. Kingston apparently thought they were funny...
     

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