mac pro 3.1 ram only shows 6gb ram... i HAVE INSTALLED 10GB

Discussion in 'Mac Pro' started by gogul1, May 3, 2014.

  1. gogul1 macrumors member

    Apr 26, 2014
    hello, bought 8gb of 800 mhz ddr2 ram for the mac pro to install. I placed all 4 of the big ram (2gb in the top tray) I put the 2 1gb ram modules in the bottom tray as that was the recommended set up. Sadly my mac shows only 6 gb of ram are being recognised. Any ideas?


    it recognises the two 1gb modules in the bottom tray (b) DIMM 1 & 2
    It recognised the two 2GB modules in top tray (a) DIMM 1 & 2
    It says that DIMM 3& 4 in the top (a) tray are not installed... but they are!


    ok I put the 2 2gb ram that was in DIMM 3 & 4 in the A tray into the DIMM 1&2 in the B tray. I them put the 1gb modules into the DIMM 3&4 in the bottom (b) tray. It now recognises all the ram.

    Can anyone confirm this is the optimal way to use the ram?
  2. m4v3r1ck macrumors 68020


    Nov 2, 2011
    The Netherlands
  3. G4DP macrumors 65816

    Mar 28, 2007
    Should tell you in the owners manual.

    But I have

    Riser A Slot 1 - 2GB
    Riser A Slot 2 - 2GB
    Riser A Slot 3 - 1GB
    Riser A Slot 4 - 1GB

    Riser B Slot 1 - 2GB
    Riser B Slot 2 - 2GB
    Riser B Slot 3 - Empty
    Riser B Slot 4 - Empty

    All 10GB shows up although I have had to swap the risers around. For some reason one of them will no longer work in the upper riser slot.

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