By PC I assume you don’t mean a Mac.
A lot depends on what DAW software and interface you plan on using as well as whether you want a rack, laptop, or minibox form factor.
And unless you know what you’re doing when it comes to specifying hardware, it might make more sense to just purchase an already configured music computer from somebody like
Sweetwater or SlickAudio. The price difference between configuring and building your own and buying one preconfigured for music apps isn’t that much these days. Plus a specialty dealer can provide tech support and a warranty.
Best bet IMO is to give a few of these specialty PC dealers a call, tell them what you want to do, and get their advice.
In general terms a music PC needs to be very quiet (i.e. no loud fans) and pack a powerful CPU (i7), plenty of RAM (16 Gb or more) and ideally have two fast HDs (a pair of SSDs or one SSD plus a very fast HDD) and have plenty of ports available.
To do it right, figure on spending around $1700-$2000 all in.