Fan problem following backplane replacement

Discussion in 'Mac Pro' started by scootscoot, Oct 19, 2016.

  1. scootscoot macrumors newbie

    Joined:
    Oct 19, 2016
    #1
    So I am working on a 2009 4,1 Mac Pro with Dual Xeon E5520's and 8 GB RAM. About 4 months ago the PSU went down. That swap went great. No issues following the swap. Unfortunately about 2 weeks ago the mac pro went out again. This time it wouldnt show any signs of power(when the PSU went out last time I could still hear some noises indicating some power). This time zero power noises. However I did find both OVRHEAT CPU LED's to be blinking red rapidly without end. I read that they are supposed to flash once when a power cable is plugged in but they flashed over and over. So I took a look around and ended up confirming the PSU was good by using the DIAG button to get the amber light illuminated but was still unable to get the OVRHEAT LED's to turn off. Obviously it was not a heating issue as the thing wouldnt even turn on so to get hot enough to overheat was out of the question. I ordered, received and installed the backplane board w/o issue and upon hitting the power button the thing fired right up. However, after a few seconds I found that all the fans kicked into high gear and spun at what sounded like full blast. My next step was to run EFI ASD. The only errors found were related to the fans themselves. No sensors reported any issues. I called the company I purchased the replacement backplane board from to report this as I immediately thought the board to be faulty and wanted some advice in testing that. When I finally got someone who could help, which took some time, they recommended checking all sensors anyway, even though I mentioned running ASD, as well as to look for some sort of metallic, shiny tape that would somehow act or assist the sensors. I had never heard of such a part actually having a role as large as that.

    Being desperate I even ordered a second replacement backplane board which still had the same fan issues. Am I crazy in avoiding "testing" the fans. I have never heard of a fan(s) causing problems like this but I guess ordering 3 fans is cheper than ordering any other part. Here are the 8 errors EFI ASD reports

    1. Fan -PS Test 1 Quick Motor Test
    system turns on motor and verifies that the motor is on quickly
    Error - motor is spinning slower than it should

    2. Fan - Exhaust Test 1 Quick Motor Test
    system turns on motor and verifies that the motor is on quickly
    Error - motor is spinning slower than it should

    3. fan -Intake test 1 qucik motor test
    system turns on motor and verifies that the motor is on quickly
    Error - Motor is spinning slower than it should

    4. fan -pci test 2 long motor test
    system turns on motor and verifies that the motor is on quickly
    error - motor did not reach target speed in time

    5. fan - ps test 2 long motor test
    system turns on motor and verifies that the motor is on
    error - motor did not reach target speed in time

    6. fan - exhaust test 2 long motor test
    system turns on motor and verifies that the motor is on
    error - motor did not reach target speed in time

    7. fan - intake test 2 long motor test
    system turns on motor and verifies that the motor is on
    error - motor did not reach target speed in time

    8. fan - boosta test 2 long motor test
    system turns on motor and verifies that the motor is on
    error - motor did not reach target speed in time

    Thanks for taking the time!
     
  2. ActionableMango macrumors 604

    ActionableMango

    Joined:
    Sep 21, 2010
    #2
    In the past this has been caused by a 2009 vs 2010 backplane mismatch. Are you sure you certain you got a 2009 backplane and not a 2010/2012? They are physically compatible and work together in every way except for the fans going crazy.
     
  3. scootscoot thread starter macrumors newbie

    Joined:
    Oct 19, 2016
    #3
    Thanks for your reply!

    Both the original board and the second replacement board have the Apple part # 820-2337-a

    I am assuming since there is a difference in function(fans) between the 2009 and 2010/12 versions that the part # would be different but please correct me if I am wrong.
     
  4. ActionableMango macrumors 604

    ActionableMango

    Joined:
    Sep 21, 2010
    #4
  5. h9826790 macrumors 604

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #5
    Check the SMC version in About this Mac -> system report -> hardware overview.

    If both SMC version are not the same. Then most likely you get the wrong logic board.
     
  6. scootscoot thread starter macrumors newbie

    Joined:
    Oct 19, 2016
    #6
    Thanks for the tip. Do you have any idea where that number would be. The only other numbers that follow a similar pattern are 630-9399 near the airport card slot on a barcode sticker and on the other side of the board on another barcode sticker near the bluetooth card slot is 631-1009. These are from my original board.


    The numbers from the replacement board do not match up. It sounds like a logic board repair will be tricky to complete without having fans running full time(without a 3rd party app) as they are in low supply with multiple versions. I'll probably continue to look for something suitable as a replacement or deal with the fan noise.
    --- Post Merged, Oct 19, 2016 ---
    Thanks for that heads up. Similar to the part numbers I am guessing this is likely the issue.
     
  7. ActionableMango macrumors 604

    ActionableMango

    Joined:
    Sep 21, 2010
    #7

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