Hi steemir, thanks for your feedback! The version of PBE I linked to is 1.4.1 by elpida. What you've provided would work as well but I found it slightly more difficult to use in that I can't modify the values in place. With the elpida version, it does work with 256k bioses for I had some of them too. Yes, the pictures I posted are for RX4x0 but the concept is the same for the RX5x0. Go ahead and leave the 300 and 1000 as is and modify the 2000 value per my guide. If you had modified the timings according to my post and not getting success, it is likely that you have 580s that came with really good timing already. Start from original rom and only copy timing from 1750 to 2000. Lemme know if that works and best of luck!