Q: Uneven display artifacts

Hi

I have a setup with 2 thunderbolt and 1 cinema displays connected to a Mac Pro 2015 (10.9.5) and over the last 5-6 months these wierd artifacts have slowly started to appear more and more.

Doesn't flicker or move, just stuck there.

It's the worst on the middle display (as shown in the picture), but it's there on all the displays.

I have all 3 displays lined up next to eachother and on each side I have an Adam A7X active studio speaker.

As I'm working in the TV-Production industry, on busy weeks, I can have the setup working several days 24/7.

It's not the usual burn because I have no crazy background (stadard dark grey) and never had any picture / program looking like this showing.

Im working on getting the speaker away from the displays on the wall instaed.

Is it possible these artifacts appears from the heavy magnets in the speakers (wouldn't explain why the middle screen is hit the worst) or is it an overheating from the displays that's slowly killing them?

Is this a known bug I'm just not aware of?

thanks!