I have Asrock h110 pro btc+ mianboard + 1200 W PSU and 5 X rx 580 ..
You mention you only have 5 pcs of rx 580s? If you aren't trying to run any more than that then it shouldn't matter. The BIOS screen is probably is displaying that the others slots are not working because you have no other GPUs plugged into them? Once you have 13 GPUs and have a real problem thats probably when you should start asking.
I think it is a problem. Since I have plan to buy 5 more cards and 4 of them will not work.
By the way I have updates bios and in UEFI all plugged black slots seems green, the empties are no color, but when I changed one of card which plugged black slots to white slots, in uefi that white slot color chage no color into red color.
![Huh](https://bitcointalk.org/Smileys/default/huh.gif)