2GB RAM reads as 1GB RAM

Discussion in 'Mac Basics and Help' started by lifeprods, Mar 28, 2009.

  1. lifeprods macrumors newbie

    Joined:
    Dec 18, 2003
    Location:
    North Hollywood, CA
    #1
    Hello mac friends,

    I just added a pair of Kingston 2GB FB DIMM PC2 6400 sticks of RAM to my Mac Pro 8-core on top of the two 1GB RAM sticks that the computer came with. I was expecting a total of 6 GB of RAM but when I go to computer info it says I only have 4GB which means that the new Kingston sticks are reading as 1GB each instead of 2GB.

    Is this bad memory or am I missing something?

    :confused:
     
  2. BlueRevolution macrumors 603

    BlueRevolution

    Joined:
    Jul 26, 2004
    Location:
    Montreal, QC
    #2
    It's possible that one of the sticks is not seated properly. Run Hardware Test from your system's restore disks and see if it registers the memory properly.
     
  3. eddietr macrumors 6502a

    Joined:
    Oct 29, 2006
    Location:
    Virginia
    #3
    You can also check system profiler -> memory to make sure the RAM in seated in the correct banks.
     
  4. BlueRevolution macrumors 603

    BlueRevolution

    Joined:
    Jul 26, 2004
    Location:
    Montreal, QC
  5. lifeprods thread starter macrumors newbie

    Joined:
    Dec 18, 2003
    Location:
    North Hollywood, CA
    #5
    The computer is reading all four sticks as 1GB DDR2 FB-DIMM 800 MHz Status - OK

    So no, they are all seated properly. But thanks. Any other ideas?
     
  6. eddietr macrumors 6502a

    Joined:
    Oct 29, 2006
    Location:
    Virginia
    #6
    I assume you moved the factory 1GB DIMM from the lower board to the upper board and then added the new ones as a pair to the lower riser?
     
  7. JediMeister macrumors 68040

    Joined:
    Oct 9, 2008
    #7
    Mac Pros in any configuration require matched pairs of memory to be on the same riser. So the 2 GB sticks should be on the same board, as should the 1 GB DIMMs. Consult pages 1 and 2 of the Mac Pro memory replacement guide in PDF form here and make sure you have placed the RAM correctly.
     
  8. lifeprods thread starter macrumors newbie

    Joined:
    Dec 18, 2003
    Location:
    North Hollywood, CA
    #8
    Thanks JediMeister!

    That was the problem. Since the stock RAM was split between the two racks I just assumed I would add the new RAM the same way. I went ahead and moved the RAM around like you said and now I have my full 6GBs.

    yeah!

    From Happy Mac Owner!! :D
     

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