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

[sixthirty]

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!

 

[Machines]

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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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!

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 .