http://www.tomshardware.com/reviews/radeon-r9-270-review-benchmarks,3669-4.html
It runs battlefield 4 on high settings at 60fps so it'll run pretty much anything.
Next gen games may need a bit more than 4GB of RAM though but you can pop in two more sticks later if needed.
Also you will want to set the CPU multiplier to 40-42 in the motherboard bios.