Please help: I have a MacPro 5.1 with Mojave. After a restart, the Mac was dead. No power up possible. Only after the short disconnect of the power supply could be switched on again. After removing a monitor output, a start sound came again. I can only connect one monitor since then. The graphics card is alright. - Only one monitor output - No recovery partition A new installation of High Sierra on another HD get the same problems. Does anyone have any advice?