Building a PC for my Brother's Birthday, Some Questions

My brother's wife approached me about building a small but powerful PC for my brother as a birthday present for him. It's been a few years since I've put something together and longer since doing something this small--are there any concerns I should be aware of?

I have a part list thrown together but any tips or suggestions would also be very welcome. He does some gaming but no like, video rendering or anything like that. Thank you!