Can you run 4,1/5,1 machine with one stick of 8GB RAM?

Discussion in 'Mac Pro' started by Sharky II, Mar 4, 2017.

  1. Sharky II, Mar 4, 2017
    Last edited: Mar 4, 2017

    Sharky II macrumors 6502a

    Sharky II

    Joined:
    Jan 6, 2004
    Location:
    United Kingdom
    #1
    Hi,

    Trying to trouble shoot some memory/hardware issues running memtestosx in single user mode.

    Obviously it's easier to troubleshoot memory problems if I do it one stick at a time - so is it OK to run only one stick of 8GB ECC (Registered... i have some unregistered I can test too) and test like that?

    I've tried putting in one stick and OSX boots and performs normally, sees the 8GB of ram.

    When booting in single user mode and running memtest though, the last 5 sticks have all caused a kernel panic/frozen/thrown an error, so I'm wondering if it's problem with only having one stick? 5 out of 8 sticks having a fault seems a bit suspicious, although it's possible - the RAM is second hand.

    I'm testing the 6th stick now...

    Cheers,

    Ed
    --- Post Merged, Mar 4, 2017 ---
    6th stick crashed... so either the board/cpus (it's a dual 6-core 3.46) is broken, or the ram shouldn't be run with just one stick - at least not for memtest.

    Anyone able to shed any light?
     
  2. h9826790 macrumors 604

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #2
    For dual processor model, the manual only says that you can run 2,3,4,6,8 sticks, never mention that you can run with only 1 stick.
     
  3. Sharky II thread starter macrumors 6502a

    Sharky II

    Joined:
    Jan 6, 2004
    Location:
    United Kingdom
    #3
    Hi,

    Yes, I saw the same thing too. But I think it's simply due to the idea that who would buy a Mac Pro and use only one stick? It's not even dual channel then.

    Anyway, I saw lots of people in another thread say that it was OK, and in fact, when I tested my fully functional RAM with memtest, there were no errors with multiple runs. I also have one of the 'new' sticks which works just fine with memtest with a single stick. OSX works just fine too.

    So, though it seems unlikely, lots of the RAM i have is faulty... maybe 6/8 of the sticks, but I need to do more testing. It seems hard to believe that so many of the 8 sticks I received (from eBay) are faulty, but that's what it looks like it.

    Cheers,

    Ed
     
  4. h9826790 macrumors 604

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #4
    If not the sticks, may be the slot itself is the problem. Some compressed air may help.

    Anyway, did you try to put the stick (only one stick) in another slot? I think the worst case is just can't boot. But if it boot, then you may run the test with another slot to determine if the slot 1 itself is good or not.
     
  5. Sharky II thread starter macrumors 6502a

    Sharky II

    Joined:
    Jan 6, 2004
    Location:
    United Kingdom
    #5
    The computer has never failed to boot - just kernel panics/sudden restarts.

    After 10 days or so of no problems (I thought the issue had magically resolved itself), I had another Kernel Panic/restart while working on a large Logic project that used lots of RAM - the Kernel Panic had 'Machine Check' references - usually a sign of memory problems. I have also seen some ECC Error messages in system profiler, however it's rarely more than 1 error.

    It's so frustrating, obviously a lot of variables changed at the same time when I upgraded my machine, but it's also frustrating because the problem is not easily repeatable, and memtest usually struggles to find issues with ECC memory.

    I'm currently running memtest86+ off a burned CD, with one 8GB stick at a time in my single CPU board with the W3690 - if I can get the memory to fail like this, then I know the issue is not the 'new' dual CPU board, so I can at least isolate the memory as one potential cause of the problems. But, i've run tons of tests on both boards where the memory passes these tests, over and over. It's so hard to force an error.

    Obviously, I'm still hoping that the problem is with the RAM and not the dual CPU board. Temps using that board were fine/spot on.

    As there were restarts with the old 2.26GHz chips in there, I feel like I can rule out problems with the CPUs. Strangely though, I can't find the kernel panic reports from when the computer had issues with the 2.26GHz chips....

    Cheers,

    Ed
     
  6. Sharky II thread starter macrumors 6502a

    Sharky II

    Joined:
    Jan 6, 2004
    Location:
    United Kingdom
    #6
    Alas, I've given up. I don't think the problem is with the RAM - the problem is with the CPU board. It rebooted/caused Kernel Panics with my RAM, and new CPUs, so, back it goes to the seller...

    Hell of a way to waste a few weeks...
     

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