Again, for the last time: the right way to get higher hashrates with AMD Polaris cards is to edit your own BIOS; the wrong way to do it is to download someone else's from the internet. The software will try to save you from your mistake by not letting you flash the BIOS from a different P/N — that's what's happening now. You might still act dumb and force the software to flash that BIOS by running atiflash in the command-line mode and with the "force" --f flag. And then there's a good chance you'll come to this forum again, saying that now all you get is a black screen when you turn on your PC.

Solution? Don't freaking do it the wrong way. Save your original BIOS with atiflash, open it with PolarisBiosEditor, edit it (put more aggressive timings in, lower voltage/clocks etc, although the clocks and voltage can be set with software as well, like overdriventool, so that's not completely necessary for now), and flash the edited BIOS back to your card. There's a link to a guide describing this all in detail in my previous post.