I've got a Dell XPS 15 which has 2 display outputs, one HDMI which is apparently driven by the onboard intel graphics card, one DP driven by the nVidia card. I've tried to setup a triple screen setup (onboard monitor, HDMI and DP) and its all working nicely except that the two monitors driven by the Intel card have some horrible visual artifacts permanently flickering on the screen.
They do not appear when taking a screenshot so its got to be something to do with the graphics card/driver. I've gone a bit retro and taken a photo of one of the screens to illustrate it.
I think I got a bit unlucky with the photo, most of the time there are way more dotted lines than that, covering the screen. They flicker around quite a lot. Interestingly while they don't appear on the nVidia-driven screen usually, if I drag a window over there then the artifacts appear around the outside of the edge of the window.
These visual artifacts do not appear when the nVidia card is disabled (so the intel card is not just broken). Its only when using nVidia prime to display on both sets of screens.
Any ideas for what I can try? It feels like I've tried every imaginable setting on nVIdia settings and on Compiz.