dimm or udimm

Discussion in 'Mac Pro' started by enny001, Jul 8, 2016.

  1. enny001 macrumors member

    Apr 30, 2013
    Hi guys i have mac pro 2009 i am looking to upgrade my memory to 32gb 1333MHz DDR3 ECC Memory dimm and latter and down the road my cpu but i usually do 3d modeling with lots of fire sims ect is there a difference between dimm or udimm

  2. haralds macrumors 6502a


    Jan 3, 2014
    Silicon Valley, CA
    UDIMM is Unbuffered RAM, which is a subtype of DIMM (Dual Inline Memory Module.) Unbuffered RAM modules directly expose all electrical chip signals to the bus. Registered RAM has signals buffered by intermediary components.
    All Mac Pros use ECC RAMs. From what I have read, Mac Pro 2009 was the first to support unbuffered ECC RAM - e.g. UDIMMs.
    More here: http://macs.about.com/od/macupgrades/qt/2009-2012-Mac-Pro-Memory-Upgrades.htm
  3. enny001 thread starter macrumors member

    Apr 30, 2013
  4. h9826790 macrumors G4


    Apr 3, 2014
    Hong Kong
    UDIMM is a sub set of DIMM. In other words. if you buy UDIMM, you are actually buying DIMM. However, if you buy DIMM, you may be buying UDIMM, or RDIMM....

    So, your questions is quite meaningless.

    For 4,1, you can use either UDIMM or RDIMM, but CANNOT mix them together. In general, single RDIMM can has bigger size (e.g. a single 16G RAM stick), which UDIMM may not have.

    So, if you want to go for large size memory, RDIMM usually is a better choice. Otherwise, UDIMM is fine.
  5. Bubalight macrumors member

    Apr 22, 2015
    udimm are non-ecc. This is normal desktop ram. It tends to be cheaper then ECC. (10600U-PC3 ram)

    ECC is what the 4,1 or 5,1 mac pro came with originally. It is slightly slower and also more expensive then Udimms but it also protects you from bit flips due to cosmic rays which helps system stability. ECC is rare in sizes above 4gb chips, 8gb are the biggest chips available. (10600E-PC3)

    Registered is the cheapest, it comes from server pulls. It is also ECC and thus slightly slower but more stable. It is available in the biggest sizes possible, 16gb. (10600R-PC3)
  6. AidenShaw, Jul 10, 2016
    Last edited: Jul 10, 2016

    AidenShaw macrumors P6


    Feb 8, 2003
    The Peninsula
  7. enny001 thread starter macrumors member

    Apr 30, 2013

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