Hello and welcome.
The anniversary 2.0 guide is based around the V2 E5 Xeons which are a bit outdated by now. Its more oriented towards a production web / database server and it sounds like what you are interested in is more of a Media server. If you didn’t already have the parts we might have directed you to checkout the NK 6.0 which is a more current media server build.
That said the E5 Xeons and the LGA 2011 platform are very impressive. You get a ton of cores, RAM capacity, and PCIe connectivity. Even the older V2 Xeons should be able to handle most anything you are likely to throw at them with a couple of execeptions.
The 2 main drawbacks you may encounter for a home media server are:
- Lack of Quick Sync Video transcoding. If you are planning on doing a lot of transcoding you will need to either add a PCIe GPU for transcoding or use an additional standalone QSV box to run plex.
This isn’t a concern if you are going to be watching the media at original quality but depending on the playback devices you may need to transcode say a high quality video down to something a lightweight playback device can handle.
- The E5 Xeon server will also draw quite a lot of power. Depending on the power costs where you live you might want to look into your idle power consumption and consider if you want it running 24 / 7.
Those things considered you are going to have a beefy high core count server that will be a lot of fun to build and use.
For the OS I would recommend Unraid. It is a great converged NAS / Media Server / docker + VM host OS that has a very user friendly interface and a large mostly welcoming community around it making it a great OS for someone starting out.