2010 Mac Pro 5,1 - No EFI/ Boot, no chime, black screen

[Diggi]

2010 Mac Pro 5,1 2x 2.93ghz Westmere
20gb RAM
OWC 256gb SSD
ATI Radeon 5780


The last time this system booted (at all) was just before I took out the GPU to try in another Mac Pro.

Once I reinstalled the GPU:

- system starts up
- front power button light illuminates
- all fans run
- gpu fan runs
- brief flash of red light from CPU/ RAM tray (on start up)

what doesn't work:

- cannot reset NVRAM (no chime after many attempts)
- dvd tray will not open from keyboard button
- keyboard caps lock does not illuminate
- red light inside scroll ball (mouse) does not illuminate

I've tried to boot into Safe Mode, Verbose Mode, every mode..... I've tried resetting SMC, NVRAM (as noted above). I've left the unit unplugged overnight (14 hours), I've taken out all RAM, removed all drive(s),


Cold restart at least 20 times.


No chime, black screen - nothing.


PSU?

Thoughts?

 

[startergo]

Have you removed the heatsinks from the CPU's during the testing on the other machine? Have you checked for broken/bent pins on the CPU tray connector?

 

[Diggi]

Have you removed the heatsinks from the CPU's during the testing on the other machine? Have you checked for broken/bent pins on the CPU tray connector?

I have not touched the CPU’s or their respective heatsinks.

 

[startergo]

I have not touched the CPU’s or their respective heatsinks.

Then I would suggest inspecting the pins of the CPU tray connector.

 

[Diggi]

By the way - I have read every thread on this and several other forums which pertain to this problem, and aside from switching out parts, or reseating CPU’s, I believe I’ve tried most things.
[doublepost=1550104239][/doublepost]I’ll do that.
However the problem started prior to removing RAM (that was the only reason I accessed it in the first place; to try and troubleshoot the problem)

 

[tsialex]

Seem a classic brick.

If you have another Mac Pro, test everything you can into the working one. If after the tests, everything but the backplane works, or you have a corrupted SPI flash memory or the backplane failed for another reason.