Faulty or wrong Memory from Crucial?

Discussion in 'Mac Pro' started by Gomff, Aug 6, 2011.

  1. Gomff macrumors 6502a

    Sep 17, 2009
    Hi All
    I've just tried to add another 8GB to my 2008 Mac Pro system and I think it's faulty, but I just wanted to check on here before sending it back.

    Currently I have 10 gigs in my system in the form of 4 x 2 GB sticks and 2 x 1GB sticks that the system came with.....Leaving 2 slots free which I planned to put the 2 x 4GB sticks in that I just bought from Crucial.

    When I put the new memory in, the system registered 10 GB still, with the slots reading empty which I'd put the new memory in. So I took all the memory out and just put in the new stuff and the machine wouldn't boot, as well as displaying a red light inside, around where the memory trays are.

    Have I got bad RAM or am I missing something? What is the best configuration to slot everything?

    I ordered using their online helper thing (drop down menus where you select system manufacturer, model and year) and they sent me "Upgrade for an Apple Mac Pro (8-core Xeon 5400 series) 2nd Gen Early 2008 system kit of 2 CT51272AP80E.M36FH0D6"

    When I google the ref number associated with the RAM, it comes up with "4GB DDR2 PC2-6400 800MHz 240-Pin ECC Fully Buffered CL5 Dimm Memory Module" but when I look at my system config, the RAM there is listed as "DDR2 FB-DIMM"....Is PC2 the wrong type or doesn't that matter?

    Many thanks for any advice.
  2. Umbongo macrumors 601


    Sep 14, 2006
    It's the right memory.

    Correct placements should be:

    Riser A:
    slot 1: 4GB
    slot 2: 4GB
    slot 3: 1GB
    slot 4: 1GB

    Riser B:
    slot 1: 2GB
    slot 2: 2GB
    slot 3: 2GB
    slot 4: 2GB

    and 4GB in each slot 1 or 1&2 on A if just using those new DIMMs.

    So if that is not working then you have faulty modules.
  3. Gomff thread starter macrumors 6502a

    Sep 17, 2009
    Thanks for replying.

    It's definitely faulty RAM. If I put one stick on one Riser and on on the other, the machine boots but reports 4GB of RAM. The other riser shows an illuminated red LED which on closer inspection corresponds to the slot the faulty stick has been placed in.

    I've got an RMA reference and I'm returning the RAM on Monday. Pain in the backside though.:(


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