Why is my monitor flickering?

I have noticed that my external monitor is flickering, and occasionally displaying vertical lines, most noticeable in the corners of the screen. After a while, the lines and flickering disappear, and reappear again, without any noticeable pattern.

I have excluded any software related issues, like GPU drivers and refresh rate settings, leaving me to believe that I’m either:

1. Facing a hardware issue with the monitor itself, or
2. Having an issue with my house electrical installation.

My monitor is still under warranty, but I want to exclude all potential issues on my end before I calling BenQ customer service. Any and all suggestions are welcome, and highly appreciated.