I suggest trying the Polaris Bios Editor v1.62 'one click timing patch' from jaschaknack
https://github.com/jaschaknack/PolarisBiosEditorThe bundled performance straps work great for most cards and take the guess work out of where you should copy the timings. Just load the original Bios in PBE after making a backup, click the 'one click timing patch' button, save the Bios and flash it to your card with Atiwinflash. With a modded Bios you also need to bypass the AMD driver signature check using the pixel patcher after you flash the card or the GPU will have a Code 43 in Windows Device Manager. BBT did a great video on how to mod a GPU Bios with links to all the programs you need.
https://www.youtube.com/watch?v=Syaf6o1SEUc