AMD GPU Problems

Hi Reddit, I had this problems for a long time, but I never found a solution to it, So, first of all my system is a: I7 7700k, 2 R9s 380 2 GB(one sapphire and one gigabyte one, I bought the gigabyte one only because the sapphire ones weren't in stock at the time). So whatevergreen fixed the booting from IGPU, but, I still have this one annoying problem, when I boot just with the sapphire card there is no problem, when I boot only with the gigabyte card I get the black screen (even booting with IGPU), same goes booting both, and yes I already tried to flash other bioses on my gigabyte card and some bioses didn't work or some had the same issue... At this point I'm officially out of ideas, does anyone in here have an idea? I hope so... (Sorry if my grammar isn't perfect but I'm Italian)

Author: @Davidescion