MP 1,1-5,1 Mac Pro 4,1>5,1 all the sudden doesn’t turn on

[Project Alice]

Today I went to turn on my Mac Pro and it wouldn’t. It made some very faint clicking sounds instead. No lights, and I’ve never had a problem with it before.

Power supply? I have another 4,1 that works but it is totally stock other than I did apply the firmware updates to it.

 

[Macschrauber]

swap the power supplies and you will sort it out

 

[amajor]

unplug all USB mouse/keboard, unplug power cord for maybe 10 minutes, try start without USB...
and sometime bad BR2032 battery can cause similar behavior...