Windows 10 v1703
8 RX 580 Gaming-X 8GB (Hynix)
Asus Prime Z270 P
Claymore 9.8

In june with my rig i got 240 MH/s to 242 MH/s, i change nothing and now, 3 month later the MH/s drop 230 MH/s, i tried aug 23 blockchain driver, the result, i got 248 MH/s, but unfortunately i met issue with stabilty not good.
On this topic I read this "It should be higher. Try increasing the -ethi to 8. My eight card mixed RX 570/570 4GB/8GB rig is getting 28.5 to almost 30 MH/s dual mining UBQ."

What is this setting? -ethi to 8