Comment # 3 on bug 102300 from fayn@mt2015.com

I find out Asus (2nd monitor) works with 1920x1080 @ 59.94Hz mode, which was
probed for my Dell monitor. I'm 99% sure Asus used to be 59.94Hz when monitor
last worked, however i can't see it in list of supported modes, only 60Hz which
doesn't work. 

AMDGPU(0): Modeline "1920x1080"x59.9  148.35  1920 2008 2052 2200  1080 1084
1089 1125 +hsync +vsync (67.4 kHz e)