I just overclocked my GTX 860M on my lenovo y50, it's my first time overclocking actually, i don't understand MHZ stuff in after burner but i just increased core clock and memory clock to the end of red line (Didn't make it reach white), right now tempreture is 51C since i am not playing anything, it reaches 60C sometimes when i play minecraft. didn't try GTA V and Dying light because i am alittle bit afraid it might do something to my gpu.