IMHO I'd do this:
i5 4000 series like a 4670k or a 4690K - (Overclocks are optional but I thought you could include it)
High end Z87 or Z97 motherboard - (Asus, Gigabyte, MSI, look for SLI/XFire support, high quality audio, lots of SATA6 ports)
8GB of DDR3 RAM - (Crucial, Kingston, Corsair, I use 8gb and even in the most demanding games *cough Watch Dogs* it's fine, speed doesn't matter but you could get 1866-2133mhz memory if you wanted I use 1600mhz.)
GTX 970 (MSI, ASUS, EVGA) or R9 290 (Sapphire, ASUS, MSI) - (I personally use NVidia cards due to the vast variety of features e.g. shadowplay, DSR, NVidia GameWorks and they are lot less power hungry however with R9 290 you ACTUALLY get 4gb of VRAM)
SSD for boot drive and key/daily apps - (I use an Intel one 160gb, expensive but scary fast and heard it's the most reliable. Also heard Samsung, Corsair and Crucial do fantastic SSDs)
HDD for mass storage - (I use a WD Black 2TB which I bought off eBay for £55 BARGAIN! Fast as heck for a 7200RPM drive and it's only used as my Steam library.)
Case - (Depends on Mobo size, but look at Fractal Design - SERIOUSLY RECOMMEND! The Define R5 is AMAZING)
PSU - I'd say always say get more tham you and make sure it's 1. a good, reliable brand and 2. it's at least 80+ bronze and has enough cables that you need down the line for SLI for example, do not skimp out here!!! (Look at EVGA, Corsair and Seasonic)
ALSO just my opinion, DON'T go for 4k JUST yet, get a 1080p and use DSR to get a 4k image on a 1080p display or buy a cheap IPS Korean display (look for them on eBay)
Cheers