Force Xorg to use CPU not GPU

If I'm using my GPU for CUDA computations and I want to use my CPU to manage the display, is there a way to get Xorg to use the CPU and the motherboard's HDMI slot instead of the GPU and its HDMI slot? Right now I'm maxing out the computational power of my GPU and Unity is really slow but my CPU is idling.

This answer: Use integrated graphics for display and NVIDIA GPU for CUDA on Ubuntu 14.04 appears relevant for you.

In summary setting up /etc/X11/xorg.conf as follows:

Section "ServerLayout"
    Identifier "layout"
    Screen 0 "intel"
    Screen 1 "nvidia"
EndSection

Section "Device"
    Identifier "intel"
    Driver "intel"
    BusID "PCI:0@0:2:0"
    Option "AccelMethod" "SNA"
EndSection

Section "Screen"
    Identifier "intel"
    Device "intel"
EndSection

Section "Device"
    Identifier "nvidia"
    Driver "nvidia"
    BusID "PCI:1@0:0:0"
    Option "ConstrainCursor" "off"
EndSection

Section "Screen"
    Identifier "nvidia"
    Device "nvidia"
    Option "AllowEmptyInitialConfiguration" "on"
    Option "IgnoreDisplayDevices" "CRT"
EndSection

Read the entire post for more details.

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According Asus Canada specs:

Integrated Graphics Processor- Intel® HD Graphics support Multi-VGA output support : HDMI/DVI-D/RGB/DisplayPort ports - Supports HDMI with max. resolution 4096 x 2160 @ 24 Hz / 2560 x 1600 @ 60 Hz - Supports DVI-D with max. resolution 1920 x 1200 @ 60 Hz - Supports RGB with max. resolution 1920 x 1200 @ 60 Hz - Supports DisplayPort with max. resolution 4096 x 2304 @ 60 Hz Maximum shared memory of 512 MB Supports Intel® InTru™ 3D, Quick Sync Video, Clear Video HD Technology, Insider™ Supports up to 3 displays simultaneously DP 1.2 Multi-Stream Transport compliant, supports DP 1.2 monitor daisy chain up to 3 displays

I suggest temporarily taking out your two nVidia cards, plugging a monitor into the on-board HDMI port and booting with a Live USB to runs tests with Ubuntu.

It is important to know your CPU. Discover this using:

cat /proc/cpuinfo | grep 'model name'

and report back.