hi everybody i have a problem and need your help
 
first i noticed that this problem happen only when using a Gigabyte motherboard and others is ok

the problem is when no display is connected to the motherboard and windows and miner is running ok if the power go down and return the system boots and miner begins till it define the gpu in miner console then it pause and doesnot mine till i plug a display in the motherboard it resume mining without any problem
this is too wired because it means i need a display for every gigabyte motherboard
please advise

let us suppose that 4 cards RX 570 4GB , RX 570 8GB , RX 580 4GB and RX 580 8GB
now we want to know how much profit you can get from them from highest to lowest in regard of electricty cost and with it this is my question
in my search i found that RX 580 8GB comes first then RX 570 4GB then RX 580 4GB in nicehash calculator and no pressence for RX 570 8GB