How is it possible that it draws 100W at idle? What is it even doing?

I use Arch derivatives for all my computers but my media server runs Ubuntu Server because it’s low maintenance. For storage I use a USB 2x HDD docking station (one of those where you just stick the HDD upright in it).

So it’s a computer that lets you remotely control another computer? Is the advantage over SSH or remote desktop etc that you can interact with stuff outside the OS, like in BIOS?