Boot Up/Restart boots up then monitor goes dark

[BJMoose]

Hi, I have a very stable Catalina 10.5.6 Hackintosh system.  Everything works perfectly including sleep, thunderbolt etc.  All software titles work as they should...FCP, OBS etc.  My only glitch comes when I'm booting the system or restarting.  The boot up goes as it should, but then, after the apple timeline gets to about 2/3, the monitor goes dark.  If I switch my monitor off and on again, the screen comes back and all is well from that point on.  This doesn't happen every time, but probably a good 75% of the time.  I'm currently using my displayport but the same thing happens on hdmi.  I've tried all the different ports etc.  This doesn't happen on my separate Windows system using the same monitor and z390 motherboard.  I also have a 2018 MacMini attached and it too does not have this problem.  I've tried with all the systems plugged into the monitor and also individually.  Any help or ideas would be appreciated. Thanks.