Comment by joeig

This reminds me of a problem I had a few years ago. Whenever I sat down on my office chair, my monitor turned black for a few seconds.

One day I started to understand what’s happening when I touched the aluminum Apple keyboard while being electrically charged. I was wondering how it was possible to get an electric shock since my Mac Mini had no connection to ground via its IEC-60320 C7/C8 connector. I learned that the Mac Mini grounds itself via DVI.

Turned out the pressure cylinder of the chair caused some kind of electromagnetic pulse, which interfered with the DVI signal and forced the monitor to resync every time I sat down.