Problem with logic board, one ram riser only...

Discussion in 'Mac Pro' started by donkeyshot, May 10, 2013.

  1. donkeyshot macrumors newbie

    Joined:
    May 9, 2013
    Location:
    switzerland
    #1
    hi all!
    i'm running a mac pro 3.1 (early 2008). never had any trouble with it until recently. after i dusted the machine it wouldn't boot anymore. the techies told me that all ram modules (original 4x1gb) are ok, the two ram risers as well (checked all that myself as well) and concluded that my logic board has a problem with the upper ram riser slot.

    i'm not running any ram intensive a/v programs. i simply want to have a fast desktop for my work related stuff. so at first i was pissed, it's some problem after all, but it didn't seem thaaat much of a difference being down to half my ram. but all this somehow coincided with my idea of several upgrades i planned (have an ssd, a better and less noisy graphics card) and ram was in my list as well...

    i can't afford 900 $ for a new logic board. some friends too told me that my desktop isn't worth it (whatever...). so yesterday i just thought i'd try what those techies told me i could not do: i put the rest of my ram into my remaining ram riser - and lo and behold, system profiler shows me i have 4x1gb ram in one ram riser! (according to mac manuals for the mp 3.1 ram shouldn't or cannot installed in the way i did...)

    do i take any risks in doing so? does anyone have an idea? had had a similar situation problem?

    looked quite some time on the net for similar cases... so i'd be really grateful for any hints and experiences!
     
  2. Tesselator macrumors 601

    Tesselator

    Joined:
    Jan 9, 2008
    Location:
    Japan
    #2
    What are you asking exactly, if your MP3,1 can be safely operated with only one riser board installed? Or do you mean with only one of them populated?

    I personally have no idea but it may be fine. There's several arguments for both sides of this. If you specifically mean only one board populated then I'm pretty sure it's not a problem at all. It's only if you're referring to operating it with one riser removed completely that some questions arise.
     
  3. donkeyshot thread starter macrumors newbie

    Joined:
    May 9, 2013
    Location:
    switzerland
    #3
    my description wasn't good. and reads like a novel... sorry
    my computer does seem operate safely - for two days now.

    however, all my ram is in one riser card, the other riser card is not plugged in at all. when i plug bot riser cards in (and consequently spread the ram on the two riser cards with each 2x1gb) then the machine does not start up.

    so my question is if there is any known issues with running a mac pro 3.1 with one fully populated ram riser card while the other one is not plugged in at all.

    what questions would arise? :)
    and thanks for the quick reply!
     
  4. Tesselator macrumors 601

    Tesselator

    Joined:
    Jan 9, 2008
    Location:
    Japan
    #4

    I personally would want to plug in the empty card even if it's kept empty. There may be some power conditioning or conditions which that card being in-place will provide. If you sill get the instabilities with that card empty then you may not have a choice but I would try it that way first.

    If the MB really is $900 without options then there's no real loss involved as $900 will buy you a MP4,1 which is a little faster anyway. Certainly $750 or so will buy you another MP3,1 in excellent condition.

    So if one way it works for awhile and then pops and the other way it doesn't work well enough to be useful then it just doesn't matter either way you're looking at a replacement. If it ends up working one way or the other then you're in luck and can postpone an upgrade or replacement until whenever.
     
  5. hfg macrumors 68040

    hfg

    Joined:
    Dec 1, 2006
    Location:
    Cedar Rapids, IA. USA
    #5
    Did you carefully inspect the socket that the RAM riser board plugs into? Perhaps a dust bunny got in there and is preventing good contact. Also, inspect the riser card itself, although you indicate that you have swapped them and the problem remains with the upper slot.

    As I recall, there was a specific order in which to populate the riser boards with RAM, so having it all on one card may slow memory access from the processors.



    -howard
     
  6. donkeyshot thread starter macrumors newbie

    Joined:
    May 9, 2013
    Location:
    switzerland
    #6
    i'll try what the both of you suggeseted - and will report!
    didn't think about buying a used machine yet.
    thanks for the common sense, i was about to get paranoid :)
     
  7. Tesselator macrumors 601

    Tesselator

    Joined:
    Jan 9, 2008
    Location:
    Japan
    #7
    Ya, hfg is right; RAM when placed in matching locations in the A and B risers can interleave much like hard-drives do in a RAID 0 stripe. When two sockets interleave it's called dual-channel and as in the MacPro 4,1 and later three can interleave for triple-channel access - not unlike a three-drive RAID 0 stripe set.

    Without that it'll operate slower like he says but if like you say you're not doing a lot of RAM intensive computations then you probably won't notice much difference. A tiny bit of snappyness maybe...

    BTW, I just assumed you had already inspected the card edges and sockets for dirt and debris or I would have mentioned that as well. If you haven't yet then I would suggest doing so. Use a very bright flashlight and a optical enhancement (a magnifying glass!) to check it out.
     
  8. Macsonic macrumors 65816

    Macsonic

    Joined:
    Sep 6, 2009
    Location:
    Earth
    #8
    Hi donkeyshot. A Mac tech guy once advised me if we encounter ram problems. we can try to use an eraser, the ones students use in school and rub it on the ram stick gold connectors or the riser card connectors to clean it up.
     
  9. donkeyshot thread starter macrumors newbie

    Joined:
    May 9, 2013
    Location:
    switzerland
    #9
    unfortunately nothing worked.

    i plugged in the empty riser card, the computer wouldn't boot.
    cleaning did not help either (i did not quite dare to use the eraser trick though, the erasers i have here are from back in school :)

    maybe i will try to find a younger generation used mac pro. seems the best bet.

    however, my computer runs without any problems so far. and that is with one fully populated ram riser card and the second one not plugged in (ram temperature is around 60° celsius average, module b2 being by far the hottest reaching some 75° sometimes).
    i'll get some new owc ram modules sometime...

    thanks again for all your posts and help!!
     

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