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MacPro Lower Memory Riser Problem

1606 Views 14 Replies Latest reply: Feb 13, 2013 2:06 PM by john6621 RSS
john6621 Calculating status...
Currently Being Moderated
Jan 31, 2013 7:52 PM

I started with a MacPro 1.1 and upgraded the following:
1. CPU from 2/dual-core to 2/quad x5355
2. upgrade graphic card to ATI Radeon 5770
3. added additional hard drive, seagate barracuda 7200 3 TB
4. memory from 6GB to 16GB
5. And after upgrade, updated firmware to 2.1 to recognize CPU


Everything went well with all the installation. BUT I noticed a red light on my lower memory board, DIMM1. (don't know if it was always there and never noticed before)  Also noticed that it showed in "About This Mac", as 16GB but in the Activity Monitor it was showing only 8GB. I tried switching the memory from top to bottom and even switch the board but I still get the red light in the lower memory board. It seems it's not reading or recognizing the lower memory board according to the Activity Monitor although it showing as 16GB in the About This Mac.


Second thing I noticed was that according to the Temperature Monitor the lower memory DIMM 3 and 4 were showing up really high 127C. So I took out all the memory and just placed 2/2GB, slot AB at top and 2/2GB, slot AB at the bottom. Red light is still there and it now shows only 4GB in the Activity Monitor. Still not reading the lower memory board. So I placed 4/2GB on top and 2/2GB on bottom, and it shows at 8GB. Now I just have 4/2GB on top only.


I tried everything possible and googled for answers without any results. I even reset PMU and nothing. I don't think it's the memory cause I switch them around in every different way in pairs. I don't think it's the memory board cause I tried switching them from top to bottom and also used a new board as well. Still not recognizing the lower memory board.


I finally ran a hardware test and "4SNS/1/4000001:TMBS" came up. I think this has something to do with the memory temperature sensor? Any idea what this error is and how to correct it?  I could really use some help....

Mac Pro, Mac OS X (10.6.8)
  • magnusalex Calculating status...
    Currently Being Moderated
    Feb 8, 2013 5:46 AM (in response to john6621)

    I do not feel qualified to answer to your problem, as I am having some memory troubles myself, but after reading the post, I'm just thinking...


    Have you tried to replace the Riser card? They are really cheap on eBay/Amazon these days.

  • Grant Bennet-Alder Level 8 Level 8 (48,110 points)
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    Feb 8, 2013 8:11 AM (in response to john6621)

    SNS is a sensor error. You have just been working in there. Did you re-connect everything?


    If you did not change out the memory it is much more likely that you disconnected or broke something else than that you have new memory temperature issues now.


    How about loading a temperature monitoring program that knows which sensor is which?

    Mac Pro (Early 2009), Mac OS X (10.6.8), & Server, PPC, & AppleTalk Printers
  • The hatter Level 9 Level 9 (58,565 points)
    Currently Being Moderated
    Feb 10, 2013 6:33 AM (in response to john6621)

    Bad FBDIMMs. Get down to a working pair.


    Wrong on equal on A and B. Ideal? yes or maybe.


    A1:A2 set one, B1:2 set two, then A3:4 and finally B3:4.


    Quad or four DIMMs has some small quad channel symmetrical memory performmance bandwidth.


    DIMMs that show up as half or not are junk bad.


    Want t here are highest quality 2x2GB $35 on Amazon. Replace and try one or two sets of those, $70 for 8GB.


    You probably  have "bad RAM" right now.


    Whose or where did you buy t he FBDIMMs?


    And naming convention while may seem overly picky A1:4 and lower DIMM slots are named B1:4.


  • The hatter Level 9 Level 9 (58,565 points)
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    Feb 10, 2013 8:36 AM (in response to john6621)

    Rule witth mixing DIMMs, esp FBDIMMs: t hey all do not get along.


    If anything does not show its correct size/density, and with just one pair.


    If any and everything does not show up properly with the "new" Riser:


    You have to have something on top "A" Riser, so if there is a problem with the logicboard that it  connects to...


    Some people try unsupported ideas:


    A1 and A3


    A1 and B1 (t his is popular misconception as some thought that was how they have to go; that is how ONE SET ONLT goes in the 2008 3,1 btw).


    WHERE did the memory come from? Are they helpful?


    FBDIMMs that do not stay under 70*C (they should and new FBDIMMs should be low 60's) they age, stress, and the cold-hot-cold thermal cycles age and stresss until they fail.

    Which is why using SmcFanControl 2.x has been a must-have for FBDIMM users.

  • Grant Bennet-Alder Level 8 Level 8 (48,110 points)
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    Feb 13, 2013 6:52 AM (in response to john6621)

    Apple insists that FBDIMMs for these Macs have a three-dimensional finned heatsink and use an Apple certified temperature sensor.


    If you have installed "any old" FBDIMMs, that may be the source of your distress.


    Also, as The hatter has pointed out both Buffered and unbuffered are available, and combinations of varying sizes and varying buffering may not mix happily.


    The basic rule dispensed here is to buy from a Vendor that guarantees:


    "It works in your MAC or your money back."



    Mac Pro (Early 2009), Mac OS X (10.6.8), & Server, PPC, & AppleTalk Printers
  • The hatter Level 9 Level 9 (58,565 points)
    Currently Being Moderated
    Feb 13, 2013 10:25 AM (in response to john6621)

    some people do use one Riser only as it is likely the motherboard that the Riser connects to.


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