Sidebar Sidebar
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

MP 1,1-5,1 2010 5,1 Mac Pro boots with one CPU, but not two CPUs

S

stufio

macrumors newbie
Original poster
Dec 16, 2023
1
0
Hello all

I recently bought a 2010 5,1 with dual CPU tray. The previous owner said it was working, but then started freezing, so he decided to sell. When I got it home, it would power on for about 5 seconds, then immediately shut off. I decided to do the "minimum configuration testing" mentioned in the Apple Technician Guide starting on page 33. Things I have done so far:
  1. I disconnected everything except the PSU from the backplane. Witnessed the OVTMP CPUA and OVTMP CPUB LEDs briefly flash when power was connected and 5V STBY LED was amber.
  2. I reinstalled processor cage with fans but NO processors, heatsinks, or memory. Powered on Mac and witnessed front and rear processor cage fans spin slowly and red error LEDs on processor board light up. The PSU PWROK LED was green, 5V STBY LED was amber, EFI DONE was green, and GPU OK was green.
  3. I reinstalled a processor into the processor A connector as well as a heatsink and one DIMM in slot 1. The SYS_PG LED was lit when the Mac was powered on. The front and rear fans spin slowly when the Mac is powered on, but then after about one minute, they ramp up to 100%.
  4. I connected a hard drive into drive bay 1 with High Sierra and a Radeon HD 5770 GPU. With one CPU and one DIMM in slot 1, the computer chimes and boots to a prohibitory symbol, then alternates to an Apple logo back and forth, but never boots to the OS. I swapped processors, and the same behavior is observed.
  5. I installed both CPUs (still with one DIMM in slot 1) and it powers up and stays on, but I never hear the boot chime or see anything on the screen. When I press the DIAG LED button, I see EFI DONE and GPU OK, but SYS_PG never comes on like it does with one CPU alone.
My assumptions from testing are: the backplane is working, the processor tray is working, and both CPUs are working (independently, but not together). I've tried resetting SMC, RTC, and NVRAM, but the problem persists. I tried holding down D while booting, but it never chimes and boots to anything. What should my next troubleshooting steps be? Any help is appreciated. Thanks!
 
You must log in or register to reply here.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.
Top Bottom
Back