I managed to reach 570khash stable on the rx 570 now with hynix memory. With latest spminer and bios patch(polarisbioseditor 1 click patch, and AMD/ATI Pixel Clock Patcher 1.4.9). The card is applied with rx 580 straps and the ATI Pixel Clock Patcher 1 removes the signature checking so the drivers don't fail.

Windows 8.1
core/mem 1370/2150
pl -15%

Stock clocks without biospatch is only 320KHASH