sounds really weird...

something i would try

-check if mainboardbios settings are right
4g decoding on, pcie = gen 1 all
disable everything you dont need

-ddu +  install new driver with device manager

for later than blockchain driver
Computer\HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\{4d36e968-e325-11ce-bfc1-08002be10318}\0002
add dword KMD_EnableInternalLargePage=2 in registry for gpu workloadmode

disable crossfire and ulps in registry
EnableCrossFireAutoLink=0
EnableUlps=0

maybe you fucked something up with bios?
reflash stock bios and recheck

are your risers alright? connect with 4 or 6pin never with sata, you wouldnt believe how many problems risers can cause

the brand is not the problem im pretty sure, i have everything mixed up...580´s/vegas from all brands working fine