Black screens

[Earnist_]

I have the ryzen 7 1700x set to 3.85 ghz at 1.378 volts , power supply is 750 w and as soon as i run cinebench my pc just black screens 

[Fred Castellum]

Can you do anything after it black screens? Crtl + Alt + Del? Or does it lock up and force a system restart? Does it restart on it's own after it the screen goes black? Any info in Event Viewer? 

[A_Game_Hacker.b1368]

try running base clocks and voltages and oc until you back screen then up the voltage.