How did you mod the bios do you change the values yourself on each card or just find a .rom on the internet for the same model/memory?
I wouldn't be dual mining sia at the moment either since the introduction of the Bitmain A3 just mine Ethereum
Download SMOS or Hive OS and try that instead of windows - see what sort of hashrate you are getting I would be looking at 28-30 as the average for an RX 580.
it wont let me send another personal msg for an hour.
when you say miner do you mean like the claymore miner
SMOS includes Claymore miner and other miners for AMD cards in the build you can download