Mac Pro 4.1 - 5.1 memory matching problem

Discussion in 'Mac Pro' started by rueyloon, Aug 27, 2014.

  1. rueyloon macrumors regular

    Joined:
    Sep 24, 2013
    #1
    Hello

    hi, I just received 4 X 8GB from my ebay purchase (one of the 4 is dead, but that's another story)

    I currently have
    4 X 4gb and
    4 X 1gb on my Mac Pro giving me 20gb in total

    I can't seem to match the 8GB with any of my existing RAM, they are all 8500 ecc ram. I can't seem to find any info about ram not matching except the 16GB modules (info from OWC).

    rgs
    rueyloon
     
  2. h9826790 macrumors 604

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #2
    Are they all UDIMM or RDIMM? You can't mix them together.
     
  3. rueyloon thread starter macrumors regular

    Joined:
    Sep 24, 2013
    #3
    Thanks I think you are right, the new RAM is stated at 8500R, my current ones is just plain 8500.
     
  4. stjames70 macrumors member

    Joined:
    Jul 5, 2009
    #4
    Same problem

    I bought certified mac ram from RAMJET to augment the six 8gb 1333MHz sticks I had on my 4,1. The two new sticks I got were placed on slots 4 and 8 -- they caused my Mac not to boot up and the front power white LED to blink quickly.

    Called RAMJET and after verifying installed memory, I found out they sent me the supported unregistered DIMMs and I had registered DIMMs in my machine.

    Ok. So they exchange the two 8 GB sticks with registered DIMMs.

    You know what? Same problem. So I am thinking.....problem with slots 4 and 8?

    So I swapped my existing slots 3 and 7 with the new memory to test the theory. And guess what? Blinking white LED of death on power button again!

    Exchanged to original ram sticks, and voila, normal boot.

    I think I may have to look carefully at the exact Hynix memory that is on that computer and try to obtain the exact same 8gb sticks.

    Geez, I will tell you if that works. But I think that when you are upgrading memory, stick with the same vendor all the way through, whomever it is.
     
  5. rueyloon thread starter macrumors regular

    Joined:
    Sep 24, 2013
    #5
    I manages to pair the 12gb that came from the nMP with the uRam in my oMP.
     
  6. 666sheep macrumors 68040

    666sheep

    Joined:
    Dec 7, 2009
    Location:
    Poland
    #6
    That's perfect way, but not a must. Specs must match, that's basically all. Don't mix 2R with 4R, registered with unbuffered etc. Vendor and memory speed does not have to be the same.
     

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