@kach1
What mobo r u using,how strong r the psu's?my friend has an issue with rx 580 xfx 4gb..he has 4 rig 6cards on each..everything is exactly the same except the mobo..2 rigs have gigabye mobos 1 has AsRock and 1 with MSI..every card is hashing around 30+mhs but the one's with MSI mobo cant go over 26 or they crash..he had to underpower and underclock the hell out of them to be stable..try to do that and see how long they will run without crashing