MP 1,1-5,1 Mac not powering off after shutdown or restart

[rosah]

My MacPro1,1 no longer powers off when I shut it down. The system shuts down, display goes dead, but powersupply and fans are still running.
Same happens when I restart it, it doesn't start-up again, just stops once the system is shut down. I hear occational sounds from the optical drive, like when it powers up in start-up.
I always have to hold down the power button to shut it off, and even sometimes when I try to start it again, it returns to that same idling state, so I have to hard-shut it off again and try again.

Any ideas?

 

[reader50]

Do you have another drive, that you can clean install macOS onto? I've seen this when the OS needed to be reinstalled. Testing it on a 2nd drive protects your working drive until you're sure a reinstall is the answer.

It could also be something macOS doesn't like on PCI or USB. In the meantime, I hope you have a current TM backup.

 

[rosah]

I actually just setup my mac from scratch and that did not solve anything.
I did however recently install a USB3 PCI Express card, that might be the problem then. (The Sonnet USB3-4PM-E Allegro)

 

[Macschrauber]

Try a smc reset

Reset the SMC of your Mac - Apple Support

The SMC is responsible for managing power on your Mac. Resetting it can resolve certain uncommon issues related to power or thermal management.

support.apple.com