I've got four displays connected to PC in such way:
DVI-D-1 | HDMI-1 | HDMI3 | DP-1
1050 | 1680 | 1680 | 1050
0 | 1050 | 2730 | 4410
My xrandr result is placed here: https://pastebin.com/DXSLHGGc
DVI-D-1, HDMI-1, DP-1 is connected to NVIDIA card and HDMI3 is connected to Intel processor.
When I place anything on the third display, which is connected directly to motherboard via Display Port, it freezes. Others displays, connected to Nvidia card, works perfectly.