Hi!
I have the same card Sapphire RX 470 4GB Mining edition. With this thread I fixed HDMI output and it works now. But works only without drivers. As soon as I install drivers, gets problematic. I tried different flashes, some are more stable, other less. Screen goes black for few seconds and works again, but after some time screen gets static snow. While this is happening, pc works just fine, (audio and blind clicks does work).
I tried few different drivers, but with no luck. Also card is not patched, I patched it too, doesn't help. I went perfectly by stages for doing this. Bios flashing also works just fine, I only screwed it first time, as I flashed bios for wrong memory type. Memory type is Samsung
Is it possible the card is broken or something?
Bios which works best is original for now.