I have a problem with my Sapphire RX 570 Nitro+ 8GB: why I get 29 MH/s on Callisto but only 12 MH/s on ETH and ETC??
try with different drivers. problem will solve same happend to me.
are u sure your driver in compute mode? i doubt it. Dag size is much higher on ETH / ETC than Callisto, thats why this could happen i guess.