MP 1.1 possible defect

Discussion in 'Mac Pro' started by Macstefws, Oct 7, 2012.

  1. Macstefws macrumors newbie

    Macstefws

    Joined:
    Oct 7, 2012
    Location:
    Denmark
    #1
    Peers,

    Got my self a second used MP 1.1 w/2x2.66GHz E51xx series today, which when powered on, just stays black screened. Fans starts, diagnostic LED for CPUB went red. So I pulled out CPU B, this turned off the LED, but no more than this. Pushing diagnostic switch makes power LED go green, first LED flash yellow and GPU flashing green, tried SMC RST also no difference.

    Should I be able to boot with only one CPU in my MP?

    Any hints are welcome on possible cause, Thanks!
     
  2. hackerwayne macrumors 6502a

    hackerwayne

    Joined:
    Feb 17, 2012
    Location:
    Kuala Lumpur, Malaysia
    #2
    CPU Diag. LED lights up does not always mean a CPU defect. It can caused by a few things.

    1. A short circuit, this happened to me before, check the DVD drive area, remove both DVD drive and try to boot the system

    2. CPU overheat, check if theres sufficient thermal paste on the CPU

    3. If the CPU was upgraded/replaced, make sure they are compatible

    You can boot with 1 processor but you can only have RAM sticks on Riser A, more then that, the system will refuse to boot.

    Quoted from Apple Support Site
    "Verify trickle power
    Diagnostic LED 1 indicates the presence of trickle power required by the logic board to begin the
    startup process. LED 1 should be yellow when the DIAG_ LED button is pressed, indicating that trickle voltage is present."

    The yellow LED means the board receive good power from the PSU. Does the Mac chimes when the CPU is removed? The LEDs indicated theres no more problem with the Mac. What is the status of the front panel white LED? Does it stays on or does it flashes? If it flashes, how many times does it flash?
     
  3. Macstefws thread starter macrumors newbie

    Macstefws

    Joined:
    Oct 7, 2012
    Location:
    Denmark
    #3
    HackerWayne,

    Thx for your kind reply!

    Ad.1 Removed DVD drive => no diff
    Ad.2 Cleaned and repasted, reseated CPU cooling towers, not a problem (no overheat LEDs light up either)
    Ad.3 Both CPU are original X5150s, never changed

    Trickle LED firm yellow light, Power LED firm green when pressing Diag SW
    No chimes at all.
    Front panel LED firm white light.

    Powering on with only CPU A & memory raiser in slot A, GPU present LED flashes green during Diag mode.

    Powering on with only CPU B & memory raiser in slot B, fail CPUB lights firm red, shortly FANs starts full throttle.

    So assume I need to start focusing on 'GPU present' flash with only CPU A? Will also try to swap CPUs to try and figure out whether it's supporting circuits or CPU that's possible broken.

    But still it should boot on only one CPU&memory board, right?
     
  4. Macstefws, Oct 10, 2012
    Last edited: Oct 11, 2012

    Macstefws thread starter macrumors newbie

    Macstefws

    Joined:
    Oct 7, 2012
    Location:
    Denmark
    #4
    Swapping CPUs it still the 'fail CPUB' LED that lights red, aka it must be on the motherboard supporting circuits that has an error.

    Also with both CPUs swapped and mounted, powered on, thus still when pressing diag sw only firm green light in power led and firm yellow in trickle led, not light at all in GPU present or EFI led. Any known common causes on mother board affecting CPU B & GPU detection/usage, like worn out capacitors or other passive/active components easily acquired and changed?
     
  5. Macstefws thread starter macrumors newbie

    Macstefws

    Joined:
    Oct 7, 2012
    Location:
    Denmark
    #5
    Further analysis...

    ...shows that PSU, Memory Raisers and Video Card are all working in my other Mac Pro 1.1 aka assuming it most be something on the motherboard, only how to easiest/cheapest go figur out and fix it, clues anyone?
     
  6. 666sheep macrumors 68040

    666sheep

    Joined:
    Dec 7, 2009
    Location:
    Poland
    #6
    Apple Service Manual states that faulty PCIe card may cause CPU LED to light.
    I've seen several MR members with this issue and bad graphics card was always the culprit. Try boot your Mac without graphics card (or any other PCIe card, if you have any) with both CPUs and risers installed.
     
  7. Macstefws thread starter macrumors newbie

    Macstefws

    Joined:
    Oct 7, 2012
    Location:
    Denmark
    #7
    Thx, only the Graphic card works fine in my other Mac Pro, so... but will give it a try, thou I just ordered a refurbished motherboard for it of eBay :)
     
  8. Macstefws thread starter macrumors newbie

    Macstefws

    Joined:
    Oct 7, 2012
    Location:
    Denmark
    #8
    Nope, still turns on the fail CPU B LED woth out any PCIe cards plugged in :(
     
  9. Macstefws thread starter macrumors newbie

    Macstefws

    Joined:
    Oct 7, 2012
    Location:
    Denmark
    #9
    Problem solved... the expensive way :(

    A refurbished/second hand motherboard solve the problem, I now have a second working MP 1.1.
     

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