MacPro 3,1 won't boot, CPU OT LED flashes after cold boot attempt

Discussion in 'Mac Pro' started by sixthirty, Jan 31, 2015.

  1. sixthirty macrumors newbie

    Joined:
    Dec 4, 2014
    #1
    My MacPro 3,1 (2008) has been working fine for a while, I left it on overnight (which i frequently do) but it had shut down this morning. Now when I try to boot it up, I see the front power light and fans start to spin for about a second or two then everything goes dead. When I check the diagnostic LEDs, the two CPU OT LED's flash once about 5 seconds after the machine dies.

    Have researched the official service guide and web sourced with limited success. Any ideas are most welcome!
     
  2. Machines, Jan 31, 2015
    Last edited: Jan 31, 2015

    Machines macrumors 6502

    Machines

    Joined:
    Jan 23, 2015
    Location:
    Fox River Valley , Illinois
    #2
    OT = Overtemp . Your Mac's CPU(s) is too hot . Safeties have kicked in .

    Remove processor(s) , remove dry thermal paste , re-thermal paste with AS5 . Reboot . If you are lucky , nothing permanent is damaged .

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    OT = Overtemp . Your Mac's CPU(s) is too hot . Safeties have kicked in .

    Remove processor(s) , remove dry thermal paste , re-thermal paste with AS5 . Reinstall CPU(s) . Reboot . If you are lucky , nothing permanent is damaged .

    reposted to ping your mail box

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    Make certain your Mac has it's power plug unplugged for thirty minutes before you remove CPU heatsinks . This is a safety precaution with this model . Read the manual please for further information .
     

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