Mac Pro 5.1 running 1600 & 1066 Ram

Discussion in 'Mac Pro' started by derb ryan, Jan 25, 2015.

  1. derb ryan macrumors member

    Apr 1, 2014
    Hey guys,

    yesterday I received a 5.1 Mac and noticed the oddly looking Ram. Turns out it was a 8GB Kingston 1600 Stick (KVR16N11/8). The cool thing though was that it was running side by side with 1066Mhz sticks with no problem. Afaik those 1600mhz sticks might be cheaper than 1300Mhz, so it worth considering if you plan to upgrade.
  2. flowrider macrumors 601


    Nov 23, 2012
    Your 5,1 is capable of running RAM at a top speed of 1333MHz depending on the CPU. However, your RAM will only run at the speed of the slowest stick of RAM installed in the machine. Therefore 1600MHz RAM run with 1066MHz RAM installed will only run at 1066MHz.

    However, in a 5,1 Mac Pro, it is best if all the slots are filled with matching RAM - Same make, model and size from the same manufacturer. And for top performance, it is also best to populate only slots 1 thru 3, since the CPU utilizes three channels for memory.


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