The build overall looks fine - more expensive than it really needs to especially for 4k gaming where an AMD R5 CPU would do just as well - but fine if you're happy spending the money.
I would definitely recommend upping the PSU to the TXm or RMx series as they are much better quality and more efficient than the VS series. TXm 650W or RM750x would be great.
If you already own the monitor, post the model number, usually written on the back. You really want the monitor to have adaptive sync. Just because a monitor is sold as a gaming monitor doesn't mean it's actually any good for gaming.