MP 1,1-5,1 Troubleshooting Mac Pro 3,1

[LyonAdmiral1981]

I'll be using this Mac Pro and the screen will go black and the fans will rev up to maximum RPM. I have dual CPU and 32 gigs of RAM, stock Nvidia GPU. I will run AHT, extended test mode, it will never repeat what happens when the screen goes black and fans rev up. I've tried swapping RAM sticks and even tried swapping the GPU, still happens occasion. I suppose it could be power, but then if it was power, wouldn't the issue occur while running diagnostics. I'm at a loss and looking for advice.

Thanks

 

[840quadra]

I have a 3,1, typing on it now.

I have only experienced the issue you are dealing with when I had a dirty connection on the cards holding RAM, or when I bumped one (sort of hard) when putting the case side back on. The only other time was when the system was providing too low of voltage to my currently installed RX580. I now have switched to injecting power to the GPU from an external power supply.

Since then, the system has been super stable.