Monitor, Graphic Card, or Too many drugs?

You don't have a strong pulse generating device around the monitor or someone is running an electric motor like a vacuum? This use to be common on TVs years ago. That looks the same.
 
Your neighbors aren't Tommy, Sally, or Dick are they? The intermittency could be outside interference or internal like when the hardware temp rises to a critical point. Open them up and give them a good cleaning to start, it can only help.
 
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