Plex has a beta version of their Hardware Transcoder running right now. If you look at this thread on their forums you will see a 64-bit version of the app available for Asustor: https://forums.plex.tv/discussion/25094 ... 1-4-0-3224 This version is Plex Pass only for now, so if you don't have a Pass you won't be able to use it...
I installed this version and then started running tests and was very disappointed that I wasn't seeing significant gains in resources. Then another Asustor user posted how he got things to work, and the results using his modifications were unbelievable: https://forums.plex.tv/discussion/comme ... nt_1362622
With the first test I went from over 300% CPU usage on 4 cores to 40% usage of a SINGLE core by one really simple thing. So here's what I did and how I did it:
Make sure you downloaded the HW Transcoder version linked above. Then open WinSCP up and point to the /dev folder. Inside that folder look for a file called "renderD128" and r-click it and then click on "File" and "Copy with path". Next navigate to the /dev/dri folder and r-click on any open spot in the right pane and select New -> Link. Put in the file name renderD128 and paste in the copied name/path in the second line. Click OK. Start and stop Plex Media Server and start your own tests.
On my 7004T I gained some very significant improvements. This is across the board on any transcoding sessions I have tested SO FAR! Other models may see the same types of gains with such a simple edit. Post here if you did this and what results you have gotten.