Random MH/S drops from 13mhs to 9mhs

Hey everyone, as the title says, on my mining rig I get sudden drops in mhs and I can't figure out how to avoid this, anyone have any idea?

Its 6x RX570 4GB Sapphire Nitro+

(Screenshot)

https://preview.redd.it/3sehopa1a9q61.png?width=1633&format=png&auto=webp&s=fb15d61838a39974e0a91504161a22baa9b3c9ec