RAM problems with nMP

Discussion in 'Mac Pro' started by Captain Click, Mar 14, 2014.

  1. Captain Click macrumors newbie

    Mar 14, 2014
    This is my first post on this forum!

    Last week my 6 core MP with 512 GB and D700's 12 GB arrived (replacing my 3.1) I had already received 64 GB RAM (Crucial) form B&H.

    After days of slow and erratic performance I suspected a hardware problem.
    I ran Geekbench to see if I could spot something.

    With the 64 GB of RAM from Crucial

    With my 12 GB original RAM that came from Apple

    Check the difference in memory performance; 326 single core and 350 mulit core for the 64 GB Crucial memory, then 2992 single core and 4335 multi core with the 12 GB that came with the computer.

    It now opens 5D3 RAW files in a second or two instead of 15 to 30 seconds!
    What a waist of time and energy it has been trying to figure out what was wrong.
  2. Average Pro macrumors regular

    Jul 16, 2013
    Dear New-B

    Welcome to the site. There are several threads about utilizing non-Apple branded RAM - i.e. problems that follow. Check out the forum and you'll find them.
  3. macines macrumors member

    Jan 15, 2013
    well, really where are those threads - haven't seen or heard of anyone who has had those issues ...
  4. lemonade-maker macrumors 6502


    Jun 20, 2009
    Yeah. Love it when people are so helpful.
  5. macines macrumors member

    Jan 15, 2013
    So finally after looking for some time now i found something here on the forums.

    This is a thread about testing a 6-Core nMP with various ram configs from "Analog Guy"(so thanks to you):


    Here's the "shipped with" apple ram results 12gb (3x4) http://browser.primatelabs.com/geekbench3/399388

    and the crucial ones 64gb (4x16) http://browser.primatelabs.com/geekbench3/399783

    If you look at these results you will notice, that acutally upgrading to 64gb should improve your score, not decrease it

    I would check back with crucial - maybe you have some defective rams there

    Also try doing this and see for the results:

  6. BayouTiger macrumors 6502


    Jul 24, 2008
    New Orleans
    So far so good with the Axiom 16gb rDIMMs from MacMall.
  7. iPadPublisher macrumors 6502

    Apr 14, 2010
    Eek... I have 64GB of Crucial sitting here waiting for my nMP to show up.

    Let us know if you get this worked out?

    Welcome to the board BTW... lots of sarcastic self-involved folks, but lots more helpful (and slightly more sarcastic) folks too. :)
  8. JQuick macrumors member

    Feb 2, 2014
    I am both surprised and pleased that your system is running normally despite such severe memory problems.

    You will definitely need to return some or all of this memory.

    Find the system information on this memory by clicking on:
    Apple Menu->About This Mac. This will bring up a window that show you graphically what memory modules are recognized and allow you to generate a system report. Run the report from the System Report button in that window, and click on the Memory tab to see a representation of your installed memory.

    You can also boot in hardware diagnostic by holding down D while powering on (as described here: http://support.apple.com/kb/HT5781 ).

    It is fast and easy to use the About This Mac tools to see what your good 12GB configuration looks like. So, it may be worthwhile to familiarize yourself with what your healthy memory config looks like.

    After doing this, you manpower off before looking at the Crucial memory to determine if some of the memory is defective, or if some or all of the memory is incompatible. At best you may find that up to 3 of the new modules might be usable.

    Here is what I would test if the system were mine.

    Visually inspect the 16GB modules. Do they look identical?
    If not, this is a problem. All modules should have matching characteristics (memory chip size, rank, capacity, speed). If only one module looks different, try installing the three matching modules and look at system information again, and rerun the benchmark.
    If pairs of modules look identical, test each pari in slots 1 and 2 to see if one pair operates significantly faster than the other.

    If the all the modules look the same. You might test each module separately in slot 1 to see if you can find a DIMM that stands out. Another approach is the divide the DIMMs into 2 pairs. Test and compare these pairs to see if one works well and the other doesn't. You can the follow up by testing DIMMs from the bad pair individually.

    Memory bandwidth will be proportionally reduced when using fewer than 4 good modules, but even on a single DIMM you should be noticeably faster than what you reported above.

    If all of the modules are identical, and each shows bad performance either in paris or singly, then your memory is probably not defective per se, but definitely the wrong type of memory.

    If the system information report identifies these modules as LRDIMMs (load reduced DIMM), then it is certainly the wrong stuff and further testing is pointless. This system requires UDIMMs or RDIMMs.
  9. Captain Click thread starter macrumors newbie

    Mar 14, 2014
    Thanks for the help and interest.
    Here is the latest update in the nMP memory saga.
    I decided to run Geekbench with one 16GB stick in slot #1 at a time, hoping to find if one of the 4 sticks was defective. To my surprise, the memory performance of each stick was good and all 4 had almost identical scores!

    Then I realized that the well performing memory from Apple (3 x 4GB sticks) was always in memory slots 1,2,3. So I tried the Apple memory in slots 2,3,4 and the performance was awful!

    Then I tested one 16BG Crucial stick in slot #4 and the performance was awful.

    Than I tested 3 16GB Crucial sticks in memory slots 1,2,3 and the performance is excellent, better than the 3 Apple 4 GB sticks in slots 1,2,3.

    It appears that memory slot 4 is somehow defective, I'll call Apple tomorrow.
    Sorry about the claim that Crucial memory was the problem.
  10. peabo macrumors regular

    Feb 14, 2008
    When I got my Mac pro, I put 64GB of Crucial memory in it instantly and one of the 4 slots would not register the RAM at all. I put the Apple RAM back in and had the same problem. After using some canned air on the slots and making sure the modules were all extremely well seated, the problem went away.

    Maybe some small debris had gotten into one of the slots that was messing up the connection somehow.
  11. macines macrumors member

    Jan 15, 2013
    Man thats really bad luck.

    Guess they ramped up production too intensely ...
  12. VirtualRain macrumors 603


    Aug 1, 2008
    Vancouver, BC
    Crazy issue. Hard to trouble shoot that... Good on you for thinking to try slot 4 with the factory sticks!
  13. orpheus1120 macrumors 65816


    Jan 23, 2008
  14. JQuick macrumors member

    Feb 2, 2014
    What you observed is consistent with slot 4 being bad, but not conclusive.

    If you live near to an Apple store it might be worth a visit. Putting a lone memory module in slot 4, or a pair in slots 3 and 4, is not a supported configuration. Any configuration outside of the supported ones ( {1}, {1,2}, {1,2,3}, or {1,2,3,4}) might confuse the hell out of the memory controller and force degraded operation.

    It is still possible that one or several of your Crucial DIMMs might be slightly out of spec. They were tested and sold as pairs, not tested and sold as a 4-way set. A quick way to rule out this final option is for someone at the genius bar to add a 4th 4GB stock UDIMM to complement your 12GB or preferably test with a stock Apple 64GB set.

    What I am saying is that memory problems can be subtle. The tests you have done still do not conclusively show a problem with the system rather than with the memory.

    If you do have to replace the system, I hope you can keep the one you have until another is available. The performance of the 48GB should be good enough in the interim.
  15. deconstruct60 macrumors 604

    Mar 10, 2009
    If the 4th slot is in fact the root cause it has far more to do with lack of testing than production ramp.

    Previous Mac Pro's shipped with a DIMM for each memory controller channel. This 3 DIMM Mac Pro standard configuration doesn't.

    If Apple never plugged anything into the 4th DIMM slot during manufacture it was never tested. All these system probalby get a lightweight system check before they go out the door. (not a "deep" burning in but "does it boot and behave normally" level of check. ).


    A simple test of both Apple and Crucial DIMMs in {2,3} should largely elimiate the "freak out" and "pair" factors.

    I'd also be quite surprised if a local Apple store had any Mac Pro 2013 DIMMs just lying around. Even far more surprised if anyting other than the standard 4GB DIMMs the standard configs come in. ( Apple is highly unlikely pre-deploying BTO parts to stores. )
  16. Stephent macrumors member

    Jan 31, 2012
    If it is not too late to return the RAM I got a great deal on superbiiz for 64GB of RAM and it is currently running great in my nMP with the exact same specs as yours. Here is the link to the RAM. It is Hynix brand who is a supplier for Apple RAM in the nMP so it might actually be the same RAM if you had ordered it from apple.

  17. JQuick macrumors member

    Feb 2, 2014
    My own system arrived a few hours ago.

    I ran a few tests to get a handle on the memory controller. It appears to be insensitive to memory location.

    After a baseline test with 4 modules installed, I ran 3 tests. {2,3,4} and {1,3,4} were comparable both with each other and with {2,3,4} posted by others. This comparison ruled out a dependance on slot 1. The only data I had seen with slot 1 empty was by Captain Click - and that result was both abysmal and untrustworthy.

    I also tested a lone DIMM in slot 4 which was in line with figures posted by others for a slot 1 single DIMM.

    So, visual inspection of slot 4, and blasting out any cruft with air (like peabo suggested) might be worth it.
  18. Captain Click thread starter macrumors newbie

    Mar 14, 2014
    I brought my nMP to the local Apple store, the Genius thought it was a faulty logic board, they kept it (gasp!) for more testing and repair. I'll let you guys know what they found. Meanwhile I am back working (I am a photographer) with my trusty 3.1 (good thing I have not sold it yet).
  19. JQuick macrumors member

    Feb 2, 2014
    It sucks that you have to wait a bit longer, but I am glad to hear that a solution is forthcoming and that you have a system to fall back on.

    I am curious to learn if they will perform the board replacement on-site. From what I have seen of the internals, it looks like it would be a rather quick procedure for the back room of an Apple store.
  20. BayouTiger macrumors 6502


    Jul 24, 2008
    New Orleans
    When I got mine I put the new ram in slots 3 and 4 and it would not start. Moved to 1&2 and it fired right up. This is with the Axiom 16GB RDIMMs.
  21. Captain Click thread starter macrumors newbie

    Mar 14, 2014
    Here is an update, I called Apple today to see if my nMP is ready. They said that they found the problem and parts are on order but have not come in yet.
  22. Captain Click thread starter macrumors newbie

    Mar 14, 2014
    Update and conclusion; I picked up my repaired nMP yesterday at the Apple store, they changed the CPU riser card, it appears that it was defective from day one. The machine is running well now.
    Memory performance looks to be very good.

    Thanks to everyone who made suggestions to help me find the problem.

    Now it's time to get to work on this puppy and pay for it!
  23. AidenShaw macrumors P6


    Feb 8, 2003
    The Peninsula
    Nice to see this terminology - the board that the CPU is on is a daughtercard, the motherboard is the circular board at the bottom of the cylinder.

    The CPU is not on the motherboard.
  24. Captain Click thread starter macrumors newbie

    Mar 14, 2014
    I have attached a screen shot of the work order indicating the part changed.

    Attached Files:

    • nMP.png
      File size:
      12.9 KB
  25. orpheus1120 macrumors 65816


    Jan 23, 2008
    Glad you have this problem sorted.

    This will be the first test I perform when I get my crucial ram and nMP.

Share This Page