Display flickering is most commonly caused by an incorrect or unstable refresh rate setting. The refresh rate is the number of times per second (measured in Hz) that a monitor redraws the image. CompTIA A+ teaches that LCD, LED, and especially older CRT displays can exhibit flickering if the refresh rate is set too low or to a value unsupported by the monitor.

For modern displays, typical refresh rates are 60 Hz, 75 Hz, 120 Hz, 144 Hz, and higher. If the refresh rate is mismatched—such as manually set above the monitor’s rated capability—the screen may flicker, blank intermittently, or show instability. Similarly, if the refresh rate is set too low, the user may perceive visible flicker, eye strain, or shimmering on the display.

Checking and adjusting the refresh rate through the operating system’s display settings (or GPU control panel) is the first and most direct troubleshooting step for flickering issues.

The LCD type (A) has no bearing on flickering once installed. Screen resolution (C) affects clarity and scaling but does not cause flicker by itself. Pixel density (D) is a hardware characteristic and cannot cause flickering.

Thus, the correct component to check when diagnosing display flicker is the refresh rate.