Yes. But if you want help, it would be better if knew details of your
monitor.
The power supply to my Acer AL1319 display caused a kind of flicker
once. I'd failed to plug it into the display securely, and the screen
would sometimes be on, and at other times not.
Yes, it can. Several low-end PS can let "static" out and depending
how far the monitor is, you can see the "effects." You can easily see
this if the PC case is opened and the monitor is just next to it.