Since this game is quite hungry for both CPU and GPU performance, then make sure that your computer rig does have good build-quality power supply unit, which can withstand power supply requirements. 600-850 Watts on paper looks solid, but if it is low-end PSU from manufacturers like Airen, Allied, ColorSit, Corsair VS (only VS line from this manufacturer), EuroCase, Evolveo, HEDY, Jersey, KME, LC Power, Mercury, Micase, ModeCom, RedStar, TakeME, Trust, Whitenergy, Xilence - then you can be almost sure, that PSU is to blame.
Of course, there might be things like overheating (CPU / GPU), so I would suggest to check these first, but if you got PSU from manufactured listed above... throw it from the window and buy quality PSU - Corsair CX is in my opinion good entry level PSU.
If none of this is to blame, then I guess the issue is elsewhere.