DIAGNOSIS: You're likely dealing with the monitor's VRR (Variable Refresh Rate) feature, specifically G-Sync Compatible or AMD FreeSync, interacting poorly with your graphics card or game. The screen blanks as it re-negotiates the refresh rate.
FIX: First, try turning off the adaptive sync feature on the monitor itself. Press the joystick button on the back, go to Game Adjust > Adaptive-Sync, and set it to 'Off.' Play your game and see if the blackouts stop. If they do, you've confirmed the source.
IF THAT DIDN'T WORK: The issue could be your DisplayPort cable. This monitor is picky about cables. Swap in a different, high-quality DisplayPort 1.4 cable that's certified for high bandwidth. A flaky cable can cause signal drops that look like black screens.
HEADS UP: If you turn Adaptive-Sync off, you'll lose the smoothness benefit. Once you've swapped the cable, you can try turning Adaptive-Sync back on. Sometimes a firmware update for your graphics card drivers can also fix these handshake issues.