The PC is going to be built for gaming
Well I am not a gamer, the nearest I come to that is Microsoft Flight Professional or was - as I do not use it now, but I do not think you will be very happy gaming, on headphones.
However that is a very minor point
Please do not apologise, it is YOUR topic, I was simply trying to say, that my colleague iammykyl, would be better placed to advise, as he stands above me in system building, when you provided the info.
The only point I would make is, you really do need to satisfy yourself, as to what the arrangements are for this build - but perhaps we may presume there is no real cost involved.
AND do NOT try and build it yourself when you are in any way limited to time, there is no rush, and no prizes for speed.
Good luck with it from me.