I've come across an issue with my MB, using Asus H81 BTC Pro R2.0 + 6x Sapphire RX580. For some reason it won't detect any card plugged into the 6th PCIe slot (rightmost) while all other slots work fine. I've tested extensively and rotated all components so I can exclude an issue with the cards, risers or cables. Reset CMOS, updated to latest BIOS, changed PCIe from Auto to Gen1 and back, using Win10.
Anyone else had this issue before? Otherwise I might just look for a new MB.
Thanks a lot!