Monitor is Jittery

I've seen this when the back of the monitor is pushed up against metal (filing cabinet, for example) or too close to another monitor, or too close to a cell phone (although it's usually an occational thing with the cell phones).

If you have a subwoofer or tweeter too close to it, it will do that too.

Yes, some device may cause electromagnetic interference. Try to clear all electric devices such as other monitors, speakers, subwoofers, power supplies etc on a distance, and also see if a monitor degauss has any effect.

putting new cpu heattsink and fan in within hours

new sink and fan are installed - no jitter and we're running at 101 on the cpu - I think we're doing a lot better now.