Hi guys. In a previous post I mentioned I was gonna try installing Catalina on my Mac Pro 3,1. Unfortunately last week my Mac Pro wouldn't start ( I don't mean boot, I mean power on). A diagnostic led turned on.The one with ERRB sign. After a small research I changed the PSU and my Mac now would power on but still no boot screen.The only options left are : motherboard and cpu replacement. I know this is not the right place to ask, but is there anything else I should try before replacing them? I've tried resetting from the motherboard but still no use. I should also mention that I did't install Catalin yet as this problem occurred before trying to do so.
This happened to me recently. The only way I got my 3,1 to come back was to leave it unplugged from power for over a week. Actually in my case it took nearly 3 weeks for it to come back but I had gotten information on the internet that a week was enough. i have no idea why this works but I'm typing on my 3,1 and I thought too that it was a lost cause.