I need help. I have been running High Sierra with no problems on a 4,1-5,1 Mac Pro with a Sapphire RX 580. Boot rom 144.0.0.0.0 been on for a while. Every time I try to install Mojave ,no matter what properly formatted drive I try to install to It says need helper, I say yes then after a couple of min it says it will restart in 27 seconds it goes dark ,shuts off monitors but power button. light stays on, I wait for an hr or more and nothing happens . I can't start the machine unless I pull the drive I tried to install on. I can then boot up from my boot drive in 13.6 ,shut down, replace the removed drive and the the machine will boot up from main drive in 13.6 . Ive done MANY erases , reformats, clones, not clones. I remove the mojave install data folder each time. Im at my wits end this is my Logic machine and I need Mojave Thank You anyone who can help . Ive searched and searched.