I'm running a dual boot with Windows 10 and Solus. My second monitor works fine with Windows 10, but when i use Solus the monitor doesn't work. I'm using a MSI Stealth gs65 with Nvidia gtx 1060. Does anyone have any clue why it is not working?

This is the output from xrandr:
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 16384 x 16384
eDP-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 193mm
1920x1080 144.03*+ 60.08 60.01 59.97 59.96 59.93
1680x1050 59.95 59.88
1400x1050 74.76 59.98
1600x900 59.99 59.94 59.95 59.82
1280x1024 85.02 75.02 60.02
1400x900 59.96 59.88
1280x960 85.00 60.00
1440x810 60.00 59.97
1368x768 59.88 59.85
1280x800 59.99 59.97 59.81 59.91
1152x864 75.00
1280x720 60.00 59.99 59.86 59.74
1024x768 85.00 75.05 60.04 85.00 75.03 70.07 60.00
1024x768i 86.96
960x720 85.00 75.00 60.00
928x696 75.00 60.05
896x672 75.05 60.01
1024x576 59.95 59.96 59.90 59.82
960x600 59.93 60.00
832x624 74.55
960x540 59.96 59.99 59.63 59.82
800x600 85.00 75.00 70.00 65.00 60.00 85.14 72.19 75.00 60.32 56.25
840x525 60.01 59.88
864x486 59.92 59.57
700x525 74.76 59.98
800x450 59.95 59.82
640x512 85.02 75.02 60.02
700x450 59.96 59.88
640x480 85.09 60.00 85.01 72.81 75.00 59.94
720x405 59.51 58.99
720x400 85.04
684x384 59.88 59.85
640x400 59.88 59.98 85.08
576x432 75.00
640x360 59.86 59.83 59.84 59.32
640x350 85.08
512x384 85.00 75.03 70.07 60.00
512x384i 87.06
512x288 60.00 59.92
416x312 74.66
480x270 59.63 59.82
400x300 85.27 72.19 75.12 60.32 56.34
432x243 59.92 59.57
320x240 85.18 72.81 75.00 60.05
360x202 59.51 59.13
360x200 85.04
320x200 85.27
320x180 59.84 59.32
320x175 85.27
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)

What is your desktop environment? Each one has a settings manager with setting monitors.
You can try it as a clone:

xrandr --output HDMI-1 --same-as eDP-1

or on the right:

xrandr --output HDMI-1 --right-of eDP-1

I use Solus with Budgie as desktop manager. I tried the command you postet, but it did not work. I got no error message, but the monitor is still not working.

I think it may be a problem with xorg. At least this is what i have found in /var/log/Xorg.0.log:
[ 4.359] (II) intel(0): Output HDMI1 has no monitor section
[ 4.359] (II) intel(0): Enabled output HDMI1

[ 4.540] (II) config/udev: Adding input device HDA NVidia HDMI/DP,pcm=3 (/dev/input/event9)
[ 4.540] (II) No input driver specified, ignoring this device.
[ 4.540] (II) This device may have been added with another device file.
[ 4.540] (II) config/udev: Adding input device HDA NVidia HDMI/DP,pcm=7 (/dev/input/event11)
[ 4.540] (II) No input driver specified, ignoring this device.
[ 4.540] (II) This device may have been added with another device file.
[ 4.542] (II) config/udev: Adding input device HDA NVidia HDMI/DP,pcm=8 (/dev/input/event12)
[ 4.542] (II) No input driver specified, ignoring this device.
[ 4.542] (II) This device may have been added with another device file.
[ 4.542] (II) config/udev: Adding input device HDA NVidia HDMI/DP,pcm=9 (/dev/input/event13)
[ 4.542] (II) No input driver specified, ignoring this device.
[ 4.542] (II) This device may have been added with another device file.
[ 4.544] (II) config/udev: Adding input device HDA NVidia HDMI/DP,pcm=10 (/dev/input/event14)
[ 4.544] (II) No input driver specified, ignoring this device.

[ 4.641] (II) config/udev: Adding input device HDA Intel PCH HDMI/DP,pcm=3 (/dev/input/event19)
[ 4.641] (II) No input driver specified, ignoring this device.
[ 4.641] (II) This device may have been added with another device file.
[ 4.642] (II) config/udev: Adding input device HDA Intel PCH HDMI/DP,pcm=7 (/dev/input/event20)
[ 4.642] (II) No input driver specified, ignoring this device.
[ 4.642] (II) This device may have been added with another device file.
[ 4.643] (II) config/udev: Adding input device HDA Intel PCH HDMI/DP,pcm=8 (/dev/input/event21)
[ 4.644] (II) No input driver specified, ignoring this device.
[ 4.644] (II) This device may have been added with another device file.
[ 4.645] (II) config/udev: Adding input device HDA Intel PCH HDMI/DP,pcm=9 (/dev/input/event22)
[ 4.645] (II) No input driver specified, ignoring this device.
[ 4.645] (II) This device may have been added with another device file.
[ 4.646] (II) config/udev: Adding input device HDA Intel PCH HDMI/DP,pcm=10 (/dev/input/event23)
[ 4.646] (II) No input driver specified, ignoring this device.

What is the resolution and refresh rate of the monitor?

    pomon

    The resolution is 1920 x 1080.
    I couldn't seem to find the refresh rate, but the response time is 2ms.

    If gnome-control-center -> Screens does not see the monitor then install Arandr. Maybe it will help.
    Try again:
    xrandr --output HDMI-1 --mode 1920x1080 --rate 60

    arandr could not detect the monitor either. When I tried the command you wrote the screen flashed for a second then this error message showed: "xrandr: Configure crtc 1 failed

    This is what I get when i type xrandr -q

    Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
    eDP1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 340mm x 190mm
    1920x1080 144.03*+ 60.08 59.96 59.93
    1680x1050 59.95 59.88
    1400x1050 74.76 59.98
    1600x900 144.00 59.95 59.82
    1280x1024 85.02 75.02 60.02
    1400x900 59.96 59.88
    1280x960 85.00 60.00
    1368x768 144.00 59.88 59.85
    1280x800 59.81 59.91
    1152x864 75.00
    1280x720 144.00 59.86 59.74
    1024x768 85.00 75.03 70.07 60.00
    1024x768i 86.96
    1024x576 144.00 59.90 59.82
    832x624 74.55
    960x540 144.00 59.63 59.82
    800x600 85.14 72.19 75.00 60.32 56.25
    864x486 144.00 59.92 59.57
    640x480 85.01 72.81 75.00 59.94
    720x405 144.00 59.51 58.99
    720x400 85.04
    640x400 85.08
    640x360 144.00 59.84 59.32
    640x350 85.08
    DP1 disconnected (normal left inverted right x axis y axis)
    HDMI1 disconnected (normal left inverted right x axis y axis)
    1920x1080 144.03
    VIRTUAL1 disconnected (normal left inverted right x axis y axis)
    VIRTUAL2 disconnected (normal left inverted right x axis y axis)

    Maybe you need to add new mode with a lower refresh rate. Try:
    cvt 1920 1080 60
    At my place:

    # 1920x1080 59.96 Hz (CVT 2.07M9) hsync: 67.16 kHz; pclk: 173.00 MHz
    Modeline "1920x1080_60.00"  173.00  1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync

    xrandr --newmode "add whatever is behind modeline"
    At my place:
    xrandr --newmode "1920x1080_60.00" 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync

    xrandr --addmode HDMI-1 1920x1080_60.00
    xrandr --output HDMI-1 --mode 1920x1080_60.00

    or
    xrandr --output HDMI-1 --right-of eDP-1 --mode 1920x1080 --rate 60

    2 years later

    @pomon
    I am having some issues with the HDMI not working at 60 fps

    acer@acer ~ $ xrandr -q
    Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 16384 x 16384
    eDP connected 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 193mm
       1920x1080     60.00*+
       1680x1050     60.00  
       1280x1024     60.00  
       1440x900      60.00  
       1280x800      60.00  
       1280x720      60.00  
       1024x768      60.00  
       800x600       60.00  
       640x480       60.00  
    HDMI-A-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 800mm x 450mm
       3840x2160     30.00 +  25.00    24.00    29.97    23.98  
       4096x2160     25.00    24.00    29.97    23.98  
       1920x1200     30.00  
       1920x1080     60.00*   50.00    59.94    30.00    25.00    24.00    29.97    23.98  
       1600x1200     30.00  
       1680x1050     59.88  
       1280x1024     75.02    60.02  
       1440x900      59.90  
       1280x960      60.00  
       1280x800      59.91  
       1152x864      75.00  
       1280x720      60.00    50.00    30.00    25.00    59.94    29.97    24.00    23.98  
       1024x768      75.03    70.07    60.00  
       800x600       72.19    75.00    60.32  
       720x576       50.00  
       720x480       60.00    59.94  
       640x480       75.00    72.81    60.00    59.94  
       720x400       70.08  

    Using your cmd forces 30 fps and it works
    acer@acer ~ $ xrandr --output HDMI-A-0 --mode 1920x1080 --rate 30

    Do you have any ideas how to fix the fps so 60 works or maybe add 1920x1080 @30 as a real choose-able or default option when selecting 1920x1080

    I raised a ticket in the dev tracker here https://github.com/getsolus/packages/issues/808