这是xrandr我的机器上显示的内容：
$ xrandr -q
Screen 0: minimum 320 x 200, current 3840 x 1200, maximum 8192 x 8192
VGA1 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
DP2 connected 1920x1200+0+0 (normal left inverted right x axis y axis) 518mm x 324mm
1920x1200 60.0*+
1920x1080 50.0 60.0 30.0 25.0 24.0
1920x1080i 50.0 60.1
1600x1200 60.0
1280x1024 75.0 60.0
1152x864 75.0
1280x720 50.0 60.0
1024x768 75.1 60.0
800x600 75.0 60.3
720x576 50.0
720x480 59.9
640x480 75.0 60.0 59.9
720x400 70.1
HDMI3 connected 1920x1200+1920+0 (normal left inverted right x axis y axis) 518mm x 324mm
1920x1200 60.0*+
1920x1080 50.0 60.0 30.0 25.0 24.0
1920x1080i 50.0 60.1
1600x1200 60.0
1280x1024 75.0 60.0
1152x864 75.0
1280x720 50.0 60.0
1440x576i 50.1
1024x768 75.1 60.0
1440x480i 60.1
800x600 75.0 60.3
720x576 50.0
720x480 59.9
640x480 75.0 60.0 59.9
720x400 70.1
DP3 disconnected (normal left inverted right x axis y axis)
我有华硕Z97-A主板其中有1 x DisplayPort和1 x HDMI输出但是Supports up to 3 displays simultaneously。这就是为什么xrandr显示 3HDMI和 3DP端口（这会很奇怪）？如果不是，为什么会这样？我目前连接了 2 台显示器，一台插入 tto HDMI，另一台插入DP.
编辑：或者这是因为daisy chain该主板支持？ AFAIK，它不适用于 HDMI，仅适用于 DisplayPort。