Just an update FYI:
I tried running Plex under UnRaid (never tried before, really user friendly setup for this Operating System). In a few hours after reading some guide my PMS under docker was Up & Running.
Now I’m able to Hw transcode every single file I have, the previous mentioned runs with barely 10% CPU usage! I tried also 4K HDR 10Bit demo and not considering the washed out colours (I kno it’s a known problem) the file plays smoot like a butter and with a VERY low CPU usage!
Maybe the Win version had problem o were problem related to the windows graphics driver I don’t know!
