14 Replies Latest reply: Feb 13, 2013 2:06 PM by john6621
john6621 Level 1 (0 points)

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 Level 1 (0 points)

    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 9 (56,466 points)

    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?

  • john6621 Level 1 (0 points)

    Thanks guys for the feedbacks.  Been away on vacation and was unable to check my emails.  First, I did try a new riser card and that wasn't the problem. 


    My Mac donesn't recogize any memory on the lower riser.  It shows up on the "About this mac" but not in the "Activity Monitor".  I use the Temperture Monitor and it also doesn't recognize the lower memory modules now.


    I'm sure I've conectected everything back and I also double checked to make sure again and didn't see anything.


    I know that you have to pair the memories and have them equal to riser A and riser B.  Since it doesn't seem to recognize the lower riser, what happens if I just put all the momories on riser A.

  • The hatter Level 9 (60,930 points)

    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.


  • john6621 Level 1 (0 points)

    I don't know if it's bad DIMMs because when I place them on the top riser, it shows up and only if I place them on the lower riser it doesn't show up.  Like I've said before, everything shows up under "About This Mac" but accorinding to the "Activity Monitor" it seems the lower DIMMs are not recognized.  Also the lower riser DIMMs don't show up on my Temperature Monitor reading.  Right now I have 2gb's on A1 and A2, 2gb's on B1 and B2.  Also have 1gb's on A3 and A4.  And according to the Activity Monitor it's only showing 6gb.  I tried switching the A1,2 and B1,2 2gb's and it still shows as only 6gb


    I've tried to narrow down the problem by first switching the DIMMs around, in pairs, and also tried a new riser without any results.  Next thing I wanted to try was perhpas just changing all the DIMMs to new ones.  I hope it's not the logic board or the slot where the lower risers sit.

  • The hatter Level 9 (60,930 points)

    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.

  • john6621 Level 1 (0 points)

    Okay, I've got all new DIMMs, the ones you've suggested.  Loaded all full and I still have a red light on the lower riser.


    On the Temperature Monitor, it's showing all the memory module A in good condition.  And it's only showing memory module B3 on the lower riser.  It's reading at 127C.


    I'm running out of things to try. 

  • john6621 Level 1 (0 points)

    Oh, on the lower riser, the red light on DIMM1.

  • john6621 Level 1 (0 points)

    I've tried installing just the A1-4 and B1,2 since the B3 was showing the high reading.  At first none of the lower B1,2 were showing any temperature reading as before but now they are both showing readings of 127C.


    I need some suggestions...please....

  • Grant Bennet-Alder Level 9 (56,466 points)

    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."



  • john6621 Level 1 (0 points)

    I've already tried new risers and it's still the same.


    I've replace all new FBDIMMs and it's still the same.


    I'm running out of things to try....


    Would it cause any problem to just run the Mac with just DIMMs on the upper riser?

  • The hatter Level 9 (60,930 points)

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

  • john6621 Level 1 (0 points)

    anything else you might suggest I could try to resolve this issue?