I have a Sapphire RX470 Nitro 8GB and ran into a serious problem with Media Player Classic and the MadVR renderer. As soon as I start playing the HDD goes into a frenzy and my system hangs until teh video driver crashes comepletly. It started as soon as I tried to watch something with the new Hotfix 16.9.2, which I installed because of other problems with my system (random freezing). On driver version 16.7.3 WHQL I could use Player just fine so it seems the issue came with the latest fixes.
Rollback is not an option because of the other issue I got with the current "WHQL" driver. Thanks for looking into it.
This is an issue which is under investigation, apologies for any inconvenience caused.