You can oc the 860K on that MB, but I don't know how high frequency you can get, because the MB has only 3+2 or 4+1 power phase count. Also you don't post what GPU you have, you may check the gta v review to see the your GPU is good enough or not.
GTA V http://www.techspot.com/review/991-gta-5-pc-benchmarks/