I have tried with only 1 GTX 1060 and 1 RX 580 in place of 2 RX 580 + 1 GTX 1050.
So, it seems the power supply has enough power to support at least 3 GPU ...
It mines correctly, until GPU temperature reach 61°C ... what is strange is that "-t 50" does not help in this configuration.
It works fine if GTX 1060 is alone ...
If someone understands this behavior ;-)
Regards,
Maxime
Did you place a temperature limit on your MSI afterburner?
Make -t 80 and see if temps still go that high.
What PSU do you have?