Help with bios mod for rx580 nitro+ 8gb. I've done the mod and there is no difference in speed

Hey guys, I just got my rx 580 today and it's only hashing around 20 mh/s. I've seen that I need to modify the bios to get higher speeds. I've done that by following the guide here: http://1stminingrig.com/are-the-rx570-and-rx580-profitable-mining-performance-review/

Also on this subreddit as well. After flashing the new modified bios there is 0 difference in hash rate, it is hashing 20mh/s. Am I missing something? I figured after bios update it would be closer to 30mh/s

Please help :) thanks