My RX580 running custom Hynix BIOS hashes way faster than their driver....or at least compared to those numbers in the graphic.
I get a return from ethOS as 28-29 per unit, but the true effective hashrate is closer to 31.
Link to the firmware for those who want to try it. I am not responsible for any issues you may have.
DO NOT USE THIS FIRMWARE IF YOU ARE NOT USING A CARD WITH HYNIX MEMORY
Main article link: http://1stminingrig.com/best-bios-rom-sapphire-nitro-rx-580-8gb-oc-hynix-memory-30-mhs
BIOS link: https://mega.nz/#!ZxQEwCDC!vSgnjdHRE0rpk7L8I95WQXPRkrT0lbrTDOcn6iQWRoI
Version 2 (I found no difference): https://mega.nz/#!R0gCkajK!OAp3e4YrXowsd-IWgAphRQdBAKEMZuO6SxZwu0U2mlk
Read the article if you do not know how to safely flash the card BIOS. Hope that helps anyone stuck in the 20-22 hash range. Happy Mining/Trading/Decentralizing!
Edit: Those hash rates are while dual mining SIA with less than 1 Mh lost on the Eth mining.