Comment # 12 on bug 102300 from fayn@mt2015.com

Arch stock kernel 4.12.13-1 still boots one monitor black, but can be restored
with xrandr.

Wayland sessions work, and they never lose signal in any situation. Xorg
sessions do randomly cause black screen
(https://bugs.freedesktop.org/show_bug.cgi?id=102956).