I have problem with older Windows 7 rig. It has 2 RX 480 and 2 RX 580, all 8GB versions. They all mine just 14MH, on both Claymore and Phoenix miner.
Equihash mining is OK though. When i mined Ethash before it was about 25MH if i remember correctly. Cards are not flashed, slightly underclocked and undervolted.
I reinstalled drivers, ended up installing newest beta. Trying to figure it out for couple of days, probably going to reinstall Windows.
Any suggestions?