The monitor began to ruffle, what's wrong with it?

Question

System administration

Turned off the light. When turned on, the monitor began to ripple. I connected another monitor, it also began to ripple. Replaced the d-sub wire - did not help. Connection via integrated video card.
Does the motherboard get kranty?)

Answer 1

Use DVI, not VGA
Crosstalk to analog connection.

Answer 2

It was similar when the current was weak in the mains.

Answer 3

Thank you all, it began to work normally by itself, I don’t know why)