I do have the same issue on Gnome 3, Wayland, F22 with an Intel Graphics Chip.

On 3840 I see the flashes quite often, and the screen sometimes turns off
completely.

On 2560 it's less flashes, and on 1920 they are gone completely.

I tried different DP connections, because I thought it might be the docking
station that has not enough bandwidth, but also the internal miniDP had that
issue.

I cannot provide a Xorg log, since I'm using Wayland.