i3 only in first screen with nvidia 331.20

My system has 4 screens, such that one pair are connected to my nVidia GTX 460 (both DVI) and the other pair to a GT 610 (one DVI, one VGA). I am using nvidia-settings version 331.20. With XFCE in xubuntu 14.04 this works as expected with all screens functional.

In i3, only the first display on the 460 is working correctly, with additional displays showing only black. I can move my mouse around these screens, but the cursor is a black X.

As per tigrezno's comment, xrandr doesdetect all the screens correctly. However i3 appears only on the first display. This post (https://faq.i3wm.org/question/315/how...) seems potentially helpful, but when I tried launching separate instances of i3 with $ DISPLAY=:0.1 i3 & these instances are incapable of interacting with each other and each have their own workspace 1. In any case ~/.xsession isn't the right file as I'm not using startx.

How can I make i3 detect all 4 of my screens?

These are the values from xrandr. I have removed the list of available resolutions for each display for brevity leaving only 1920x1080 60.0*+.

  henry@kuru:~$ xrandr --screen 0
  Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 16384 x 16384
  DVI-I-0 disconnected primary (normal left inverted right x axis y axis)
  DVI-I-1 disconnected (normal left inverted right x axis y axis)
  DVI-I-2 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
     1920x1080      60.0*+
  HDMI-0 disconnected (normal left inverted right x axis y axis)
  DP-0 disconnected (normal left inverted right x axis y axis)
  DP-1 disconnected (normal left inverted right x axis y axis)

  henry@kuru:~$ xrandr --screen 1
  Screen 1: minimum 8 x 8, current 1920 x 1080, maximum 16384 x 16384
  DVI-I-3 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
     1920x1080      60.0*+

  henry@kuru:~$ xrandr --screen 2
  Screen 2: minimum 8 x 8, current 1920 x 1080, maximum 16384 x 16384
  DVI-I-0 disconnected primary (normal left inverted right x axis y axis)
  DVI-I-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
     1920x1080      60.0*+
  HDMI-0 disconnected (normal left inverted right x axis y axis)

  henry@kuru:~$ xrandr --screen 3
  Screen 3: minimum 8 x 8, current 1920 x 1080, maximum 16384 x 16384
  VGA-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
     1920x1080      60.0*+

My /etc/X11/xorg.conf was generated by nvidia-settings. I do not have Xinerama enabled.

    # nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings:  version 331.20  (buildd@roseapple)  Mon Feb  3 15:07:22 UTC 2014

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0" 0 0
    Screen      1  "Screen1" 1920 0
    Screen      2  "Screen2" 0 1080
    Screen      3  "Screen3" 1920 1080
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
    Option         "Xinerama" "0"
EndSection

Section "Files"
EndSection

Section "InputDevice"
    # generated from default ...