CPU i3 4160
GPU 270x, 280x, or gtx 960, whatever you can afford. The gtx 960 consumes less power but is less powerful than the 280xhttps://www.youtube.com/watch?v=XY2_MFEsANg
RAM 2x4 gb of 1600mhz CAS 9 or less
motherboard h97 annevesary or b85m pro4 or h97 pro4
hdd wd blue 1tb or seagate barracuda
case: whatever you like. i recommend the source 210 and corsair 200r
PSU: Get a tier 1 or 2 PSU that is at least 500W for this build here - http://www.tomshardware.co.uk/forum/id-2547993/psu-tier-list.html
The power supply is the most important part that you want to invest in. The gpu is definitely what affects performance in games the most.