Mac Pro 3.1 shows only Ram B1 and B3

Discussion in 'Mac Pro' started by Langkampfen, Aug 28, 2016.

  1. Langkampfen macrumors newbie


    Jun 1, 2014
    Got me a while back a Mac Pro 3.1 with 320 GB Harddrive and 4 GB Ram.
    Had a Stick with 2 GB on A1 and 1 on B1 (all OK
    Got me some used Ram and put on A1 and A2 2 GB each. On B1 and B2 1 GB, and A3 & A4 & B3 & B4 512 Mhz each
    It only showed up 5 Gb on Rise a. Riser B was shown as empty
    I removed all 4 512 Mb Ram and it only showed 1 GB on B1
    Now i ordered 16 GB from Amazon. 2 Gb each Stick from one Seller and each the same Lebel on.
    Mac only is showing 2 GB on B1 and B3 too. All other shown as empty.
    I swapped the Riser with same Result.
    I remove Riser A and Light on Boot Button is flashing (not booting)
    In that Case the Ram on Riser A musst be recognised,otherwise it wouldnt boot.
    The only other Thing what i did was upgrate of El Capitan from 10.11.4 to 10.11.6 between all OK and not recognising some Ram.
    Its a early 2008 8 Core 2.8 ghz with 960 Gb Crusial SSD
    Thanx for your Time
  2. handheldgames macrumors 65816


    Apr 4, 2009
    Pacific NW, USA
    Hmmmm. any dust build up? Have you swapped ram riser positions?

    Sounds like a stack of mixed working / failing Ram. is everything the same speed / type / chip manufacturer?

    Try 2 dimms in a1/b1. If successful, remove ram and set aside and repeat to verify ram. after having know working ram, From there id test a full stack of tested ram each card.

    it ccould be the new ram, a ram riser failing, or even a tired power supply.
  3. Langkampfen thread starter macrumors newbie


    Jun 1, 2014
    Hi. thanx for quick Reply.
    I got used Ram and,yes. I swaped Ram and i swaped Riser and it just recognises B1 and B3.
    Before i had that Problem i updated El Capitan from 10.11.4 to 10.11.6 but have no Hardware Test on it. Boot with holding D or Option and D is unsuccessful.
    So,Riser cant be faulty as it works when i swap it and Riser A was recognised before OSX update. Otherwise i would have ordered a other Logicboard on Ebay.
  4. TonyK macrumors 6502a


    May 24, 2009
    Any updates? I have a 3,1 but still running 10.10. Just too many concerns about 10.11 and now between this and USB issues I've read about not sure I will upgrade. May even downgrade the 2 laptops to 10.10 from 10.11.
  5. nigelbb macrumors 65816

    Dec 22, 2012
    I have had a couple of 2008 Mac Pro 3,1s from new & almost every time I have ever done any reconfiguration of the RAM it has required multiple reseating of the RAM & risers before all the RAM was recognised. Once it was all working it stayed working you just need to persevere.

    667MHz FB-DIMMs pulled from Dell & HP Xeon servers can be bought cheap on eBay. 32GB can be found for as little as $50-$60. Performance is all but identical to that of the Mac only 800MHz parts with massive heat sinks although even these parts are much cheaper than the used to be $100-$150 for 32GB. I suggest getting some new FB-DIMMs & carefully cleaning all contacts.
  6. NY Guitarist macrumors 65816

    NY Guitarist

    Mar 21, 2011
    I can add +1 to the data for having to reseat riser cards. At one point I had to reseat them a few times to clean the connectors; haven't had a problem since.
  7. TonyK macrumors 6502a


    May 24, 2009
    My own 2008 has been upgraded for memory multiple times and I've not had any issues.

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