Thank you for this write up! I have some XFX 580 cards that were not going over 21Mh with ethOS; I switched to Claymore and that brought them up to 22MH/s; I tried making some tweaks with the bios, just using the ethos atiflash command to save, and then making the modifications on another windows machine using WinSCP to copy the files back and forth; I was able to get them running at 25mH/s with the timing, but the Memory MHz any changes to the 2000 up to 2100 (got 19mHz) then 2200 (got 20mHz), so I dropped that back down to 2000, not sure what is going on there, but there is also a 300Mhz and a 1000Mhz entry in my Memory timings; I noticed you didn't have the 1000Mhz entry; any ideas on what I could be doing wrong, or are these cards just maxed out? Actual model number is RX-580P8DFWR, and it looks like it exceeds the specs on the RX-480 Black Edition, so I'm wondering if there is a way to get it go higher, get an extra 5mH/s out of it. Oh, and BTW, the Polaris software you linked to, would not open my BIOS files as mine were 256K; I had to use a newer version that I got from here: https://github.com/jaschaknack/PolarisBiosEditor
RE: Basic Guide: Mining Ethereum with RX400/RX500 GPUs