Mac Pro 3,1 won't boot after suspected RAM riser failure
My Mac Pro (3,1) has been my daily work from home driver and had an unexpected shutdown while I was having a break a few days ago. I came back to the computer thinking it had gone to sleep but it wouldn't wake, or boot properly. It powers on but doesn't chime or show any display.
I had a similar issue a few years back and found that one of the risers had a leaky cap which was preventing it from booting (but fans were full blast instead of off), so I looked at the remaining riser. I found that a bug or something must have got in and died on it and corroded a bunch of pins on DIMM1.
What I have tried:
- Bought another riser and tried multiple different (good) RAM sticks in it
- Put the riser into the empty slot below
- Removed the GPU, tried another GPU known to work
- Removed all drives
- Remove power cable for 15s while holding the power button, and booting again
- Removed Lithium battery, drained power to machine, tried a new battery
- Cleaned the bad riser and tried it again
What happens every time with all of the above troubleshooting:
The machine powers on, but no fans run and it doesn't chime. The only fan that runs is the GPU. All LEDs on the riser light up, even if there's only one or two sticks in it, and when it's placed in each riser slots.
Diagnostic LEDS:
At one point when I ran it Both OT A and OT B were red, all other LEDS were off. This only happened once and I haven't been able to replicate. Now every time it runs I get the following diagnostics:
- SLP: off
- STBY: orange/yellow
- ERRB: off
- ERRA: off
- OT B: off
- OT A: off
- GPU: green
- PWRG: off
- EFI: green
Any idea what is going on? Has it shorted and fried the main board or is there something else I can try?
Mac Pro