Advice from evga for their cards but I suspect its no different if its a nividia card and you have another brand. Checking for frame rate drops when the issues occurs may help you identify if this is the problem.
Question / Issue
With a 144Hz display, I get flickering sometimes. How do I fix this?
Answer / Solution
"This can be caused by the monitor's higher pixel clock needing the card to run at a higher speed. If the card's GPU downclocks too far, or if your frame rate drops too far below the 144Hz refresh rate of the monitor.
In the Nvidia Control Panel under 3D Settings, change the Power Management setting to "Prefer maximum performance". You may also need to set "Multi-display/mixed-GPU acceleration" to "Single display performance mode".
Enabling VSync can also help, as well as lowering the refresh rate if you are not getting close to 144 FPS."
From what I can see lowering the refresh rate from 144 mhz to 120 mhz seems to work for most.