My cards are RX580 and I need 7 slots
AsRock H110 PRO BTC+ (s1151, Intel H110) with 12 PCi-e 1x + 1 PCi-e 16x
Asus B250 MINING EXPERT (s1151, Intel B250) with 18 PPCi-e 1x + 1 PCi-e 16x and 3 ATX 12v
P.S. Asus B250 MINING EXPERT remains 12 slots for upgrade
