Diagnosis
This is typically a handshake issue between the monitor and the video source, often related to the HDCP (High-bandwidth Digital Content Protection) protocol or a failing/loose cable.
How to Fix It
1. Replace the current HDMI or DisplayPort cable with a new, certified 'High Speed' cable. This is the most common fix.
2. Ensure the cable is securely plugged into both the monitor and PC/laptop.
3. On the monitor OSD, navigate to 'Menu' > 'System Setup' > 'Input Control'. Disable 'Auto-Switch Input' and manually lock the input to your source.
4. Power cycle: turn off the monitor and PC, unplug both from power for 60 seconds, then reconnect.
If That Didn't Work
Update your graphics card driver to the latest stable version from NVIDIA, AMD, or Intel. Outdated drivers can cause intermittent handshake failures. Also, try a different video output port on your PC if available.
Heads Up
If you are using a cheap or passive DisplayPort-to-HDMI adapter, this is a frequent point of failure. Use a direct cable connection where possible. The monitor's 'DP 1.2' setting in the OSD should be left on 'Enable'.