I just setup my Plex Media Server with Qnap 451+ (4bay) 16GB Memory Quad-core Intel® Celeron® 2.0GHz (burst up to 2.42GHz)
The stock memory is 2GB but I upgraded to 16GB as I read that PMS is CPU and RAM hungry when in use.
I got everything installed to my home network and used the Qnap 451+ HDMI out to my Sony Bravia XBR43X800D 4K HDR with Android TV
I have about 200 blu-ray movies and started the process to convert for nas storage using freeware makemvk and handbrake.
I grabbed the very first blu-ray in stack of 200 (Braveheart 1995) and converted and added to my Plex library.
The Qnap 451+ Nas has a pre installed OS: QTS 4.2.0 that looks good but not all that user friendly ( I had to click and learn)
wish they has one click setup wizard button for plex media server =)
2 things I don't like about the Qnap 451+....
Plex App installed (updated to latest version ) does not work smooth with lots of glitches like 4 movie buttons and 3 search buttons on screen plus the Qnap remote only works on some of the buttons and hard to navigate!
When I use the Plex App installed on my Sony 4K HDR Android TV the App is smooth and easy to use and navigate.Qnap says the CPU will automatically increase the processor's clock rate from 2.0GHz to 2.42GHz when needed for CPU-intensive tasks and yet when I playback my blu-ray movie Braveheart it will start to stutter and freeze even after compressing the .mkv file down to 2.3GB via handbrake.