I don't intend to run either at the same time, Plex will be in the evenings and the VM will be during the day, though this will also not be intensive either. Mostly for updating some PHP code and to get Ubuntu off my local disk.
Most of my media files are HVEC files so the i7 3770 will not be suitable? I also have an old 1050ti I could drop in to the board as well, if that will help transcoding or is that entirely the CPU? My current NAS has an Intel Atom D2701 and runs the HVEC files without issues. As for the i3, instead of Intel I could also go AMD on a similar board of size (micro-ATX).
The devices used to play the files are Mii TV Boxes if that would make a difference? Remote or on mobile, we do not use at all.
The VM will not be active at all, not an all day device, I use my Mac as my daily driver and my Desktop machine for gaming and so forth. That runs an i5 9600K on an SUS ROG Strix B360-F board and 32GB DDR4 and an RTX2080, which is slight overkill for my games. Would that CPU and motherboard and RAM be more suited for the NAS? If running a VM on the NAS will be costly to my other processes I will refrain from doing so, I will then map a drive to my PC and use said as the drive for storage to be used in the VM and still keep the VM on my desktop but the storage and ISO on the NAS?
My main thing is running Docker containers. I forgot to mention MySQL as well in a container and some smaller one like Pi-Hole and so forth. As for running a VM, I could spin up a docker container with NGINX and PHP and use that instead of the VM as that is what the main use of the VM will be for.
Thanks @Hoopster for the info so far