Being a klutz I’ve never attempted building my own DAW.
But I am a big proponent of using custom PCs that are built for audio.
One thing the folks that build them do is test the various components for how they behave in an audio production environment - which is different than a general purpose PC, especially related to real-time processing. So I’d recommend taking a look at the offerings from a few custom DAW builders and see what components they are using (and avoiding) in their machines. That way you can use their research for free. 
My last few PCs were built by these folks