Forget Unraid. It's unnecessarily overcomplicated for beginners, lots of settings hidden in config files instead of a neat web interface, and quite a few parts of the array management are not named well or proper.

Instead use TrueNAS SCALE. Ubuntu based (though you can NOT treat it as Ubuntu, sadly), straightforward web interface, straightforward array naming, with lots of good tutorials.

App installation is then as simple as running the right apps from their app store. It uses Docker under the hood, config is pretty straightforward again (almost everything is mapped for you, you'll just need to add your media mount paths, which have a nice UI picker), and you're done.

Don't forget the *Arr suite (Sonarr, Radarr, Lidarr, plus whatever replaces Readarr, Prowlarr for torrent trackers), qBittorrent for client, and Bob's your uncle.

The 4790K might not be enough for transcoding (it's not about raw power but supporting the right codecs in hardware), and the 970 combo might eat more power than selling your rig and buying a NAS, but it's definitely a serviceable setup.