RAM upgrade doesn't recognize 2x512MB

Discussion in 'Mac Pro' started by joachim, May 30, 2007.

  1. joachim macrumors member

    Apr 6, 2007
    After reading about RAM configurations and how to install them, I purchased 4x1GB modules from OWC and kept the stock 2x512MB RAM. Here's how I arranged them:

    Riser A: 2x1GB at the front, 2x512MB at the back
    Riser B: 2x1GB at the front, none at the back

    For a total of 5GB. After booting up, the Mac only recognized 4GB. I thought something might be dead, so I took out the 2x512MB modules and booted again, and it told me 4GB, which is correct.

    My question is, was my system supposed to recognize the 2x512MB modules, or are they not supposed to be there in the first place?
  2. TimJim macrumors 6502a

    May 15, 2007
    try putting the 2x512 in riser b back and see what happens
  3. CanadaRAM macrumors G5


    Oct 11, 2004
    On the Left Coast - Victoria BC Canada
    Yes, it is supposed to recognize all of them.

    Check in System Profiler to see which sockets are reporting how much RAM.

    Often, this is a case of incomplete insertion in the socket.
  4. joachim thread starter macrumors member

    Apr 6, 2007
    CanadaRAM: Yep, you're correct. I installed the 2x512MB modules again and now it says 5GB of RAM. Thanks for your help.

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