Hi, I'm new here and hope someone can help.
My MacPro 2009 is running High Sierra (10.13) because of legacy audio hard- and software.
The RX580 graphics card is working great with four monitors, but it is a dual-boot system that is also running Mojave (10.14), and for some reason the RX580 then only supports a maximum of three monitors. I've seen this Mac running Sonoma and then...it does support four monitors. For various reasons I need to be able to run Mojave too, but can anyone tell me why I can use only three monitors then?
Best regards,
Henk