i have asus 2gb rx 460 dual card. i succesfuly flash Sapphire RX 560 2048 MB BIOS hynix bios to my card..But 1300 mhz not stable. i underclock to 1250 mhz gpu speed and overclock to memory speed 2000. it is stable for daily use. Also fan speed is very low beside orginal bios.My card doesnt have any power plug but sapphire has.No problem so far. Maybe 1300 mhz unstability depends on power i dont know.
The only change was the memory module, nothing else, or you have driver problems ( did you uninstalled drives with DDU before flash? ) or the BIOS on TPU does not fit your card.
So I tried out other RX560 4GB card BIOSes with Micron from TechPowerUp site
Sapphire PULSE RX 560 OC 4 GB - works but saw GPU throttling when running Heaven benchmarks (68deg)
XFX,4GB DF Radeon RX 560 4GB - works but temp runs a bit high when running Heaven benchmarks (76deg) - not sure what the DF designation means ?
XFX,4GB SF Radeon RX 560 4GB - seems to work with better temp when running Heaven benchmarks (75deg)
Happy with my MSI RX460 OC 4GB (SF) running on the XFX,4GB SF Radeon RX 560 4GB BIOS