Interesting! I'm also using the 470 generation. Since my driver change to nouveau, my 2nd Monitor has been ignored, and so has the HDMI audio output. Even after I switched back to proprietary drivers - which in turn did not crash neither SH3D nor FLE anymore.

Anybody got a left-over, maybe outdated, non-nvidia PCIe graphics card for fair money? All I want is to drive one 3840×2160 and one 1920×1080 display, no gaming, even fine @ 30 Hz. PMs welcome.