Can Mac Pro 3.1 run 667 RAM

Discussion in 'Mac Pro' started by Gothboy1, Mar 5, 2017.

  1. Gothboy1 macrumors member


    Jan 9, 2015
    So I just recently purchased a refurbed Mac Pro 2008 and it came with 2 4GB 667Mhz DDR2 FB-DIMM memory modules. These modules are covered on both sides with a metal sheet so I don't know if that's right? This machine is replacing my 2006 1.1 that stopped booting fully some months ago. From what I know the 2008 3.1 Macs used 800Mhz DDR2 240 Pin Fully-Buffered DIMM modules. Can this 2008 use 667 modules safely?

    If so can I pull the rest of the matched pair 667 modules from the old 1.1 and use them in the 2008? I guess the slot config is the same?
  2. chrfr macrumors 603

    Jul 11, 2009
    The slower RAM will work fine in the 2008, and you'll almost certainly see no tangible decrease in performance.
  3. orph macrumors 65816

    Dec 12, 2005
    i used 667 ram in my 3.1 as it was a lot cheaper to buy, if you mix it with the faster ram then all the ram will clock down to 667.

    but as chrfr mentions there is no real speed change and the gain from having more ram can be big.
  4. Gothboy1 thread starter macrumors member


    Jan 9, 2015
    Cool Guys thanks! I moved the RAM from the 2006 to the 3.1 and it now has 20 GB of RAM. Love that!

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