Monitor detection issue

I have my monitor connected via DVI (it’s an old AOC) and also connected via HDMI to a HDMI 5 way switch which is output to a TV. When the TV and the switch are off the PC randomly makes the ‘device detected’ sound and reframes the monitor as though I have just plugged in another monitor, it kind of shrinks the screen a bit then goes back, if that makes sense. Cant seem to figure out whats causing it.