How to connect 3 monitors to 2 Nvidia cards in Ubuntu?

Question

linux

Good afternoon!
Faced such problem, I can't connect 3rd monitor on Ubuntu 16.04 with native Nvidia 3xx drivers.
Two monitors (on one video card) are recognized and work, but the third (second video card) is not recognized.
The cards are connected by an SLI bridge. Setup : * Acer
G246HYL
(1920x1080) | x3
*Nvidia GTX780 | x2
* Ubuntu 16.04
* Nvidia drivers 361.42
I understand that the problem is most likely with xconf, but my knowledge is critically lacking (so I ask you to chew like a fool). If it does not complicate you, please write the required config for xconf.
xorg.conf :
Generated by nvidia-xconfig

# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig:  version 361.42  ([email protected])  Tue Mar 22 18:37:28 PDT 2016

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0"
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
EndSection

Section "Files"
EndSection

Section "InputDevice"
    # generated from default
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/psaux"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"
    # generated from default
    Identifier     "Keyboard0"
    Driver         "kbd"
EndSection

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Unknown"
    HorizSync       28.0 - 33.0
    VertRefresh     43.0 - 72.0
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

----------------------------------------------------------------------------------------

nvidia-xconfig --query-gpu-info

Number of GPUs: 2

GPU #0:
  Name      : GeForce GTX 780
  UUID      : GPU-11111111-2222-3333-4444-555555555555
  PCI BusID : PCI:1:0:0

  Number of Display Devices: 2

  Display Device 0 (TV-0):
      EDID Name             : Acer G246HYL
      Minimum HorizSync     : 31.000 kHz
      Maximum HorizSync     : 75.000 kHz
      Minimum VertRefresh   : 56 Hz
      Maximum VertRefresh   : 75 Hz
      Maximum PixelClock    : 180.000 MHz
      Maximum Width         : 1920 pixels
      Maximum Height        : 1080 pixels
      Preferred Width       : 1920 pixels
      Preferred Height      : 1080 pixels
      Preferred VertRefresh : 60 Hz
      Physical Width        : 530 mm
      Physical Height       : 300 mm

  Display Device 1 (TV-3):
      EDID Name             : Acer G246HYL
      Minimum HorizSync     : 31.000 kHz
      Maximum HorizSync     : 75.000 kHz
      Minimum VertRefresh   : 56 Hz
      Maximum VertRefresh   : 75 Hz
      Maximum PixelClock    : 180.000 MHz
      Maximum Width         : 1920 pixels
      Maximum Height        : 1080 pixels
      Preferred Width       : 1920 pixels
      Preferred Height      : 1080 pixels
      Preferred VertRefresh : 60 Hz
      Physical Width        : 530 mm
      Physical Height       : 300 mm


GPU #1:
  Name      : GeForce GTX 780
  UUID      : GPU-66666666-7777-8888-9999-000000000000
  PCI BusID : PCI:2:0:0

  Number of Display Devices: 1

  Display Device 0 (TV-0):
      EDID Name             : Acer G246HYL
      Minimum HorizSync     : 31.000 kHz
      Maximum HorizSync     : 75.000 kHz
      Minimum VertRefresh   : 56 Hz
      Maximum VertRefresh   : 75 Hz
      Maximum PixelClock    : 180.000 MHz
      Maximum Width         : 1920 pixels
      Maximum Height        : 1080 pixels
      Preferred Width       : 1920 pixels
      Preferred Height      : 1080 pixels
      Preferred VertRefresh : 60 Hz
      Physical Width        : 530 mm
      Physical Height       : 300 mm

----------------------------------------------------------------------------------------

lspci -k :

00:02.0 VGA compatible controller: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics Controller (rev 06)
  Subsystem: Gigabyte Technology Co., Ltd Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics Controller
  Kernel driver in use: i915
--
01:00.0 VGA compatible controller: NVIDIA Corporation GK110 [GeForce GTX 780] (rev a1)
  Subsystem: Gigabyte Technology Co., Ltd GK110 [GeForce GTX 780]
  Kernel driver in use: nvidia
--
02:00.0 VGA compatible controller: NVIDIA Corporation GK110 [GeForce GTX 780] (rev a1)
  Subsystem: Gigabyte Technology Co., Ltd GK110 [GeForce GTX 780]
  Kernel driver in use: nvidia

Answer 1

In SLI mode, video outputs of only one video card are used. For three-monitor work, you will either need to remove the bridge or add a third video camera.
www.nvidia.ru/object/sli-technology-multimonitor-r...