You can't play UHD discs with PowerDVD on AMD systems. That's the grim, fatalistic news I got about an hour ago. It's new to me, but it's been a long time coming.
It's lost to the mists of time when Intel joined the BDA, but regardless, AMD never hopped on the bandwagon. We'll never be privy to the reasons AMD isn't a part of the consortium; could've been that negotiations fell through, could've been that there never were any negotiations, maybe they never thought to join, maybe AMD took a look at the streaming market and decided physical media was a lost cause, maybe the expense of paying into software development and lawyer fees wouldn't be worth the effort, maybe they have some kind of deal with Microsoft that makes producing parts for UHD-capable players and consoles a competitor to their own PC platforms, maybe they didn't want to give Intel anything they could use to get an edge on AMD, or maybe Intel put a sign outside the BDA treehouse that said "No AMD nerds allowed."
While we can speculate about why AMD isn't a part of the BDA, the end result is that there is legitimate consumer player software compatible with AMD PCs. There's a proprietary Intel instruction set called SGX; PowerDVD requires SGX in order to play UHD discs, which leaves AMD out in the cold. There's nothing inherently special about SGX aside from it being an Intel-exclusive technology; AMD has equivalent DRM protective instruction sets, but due to their lack of being in the cool kids clique, AMD's tech isn't whitelisted.
AMD might be missing out on who-knows-how-many millions of dollars in royalties from UHD Blu-ray and software sales, sales from AMD-based HTPCs, and long-term investor buy-ins, but who am I to question AMD's business decisions.