How to Set the Primary GPU on Linux Systems with Multiple GPUs

1. Check Your GPUs

First, verify which GPUs are available on your system:
     

lspci | grep -E "VGA|3D"

You’ll see entries like:

00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 630
01:00.0 VGA compatible controller: NVIDIA Corporation TU106 [GeForce RTX 2060]

This shows you have both Intel and NVIDIA GPUs.

2. Identify GPU Drivers

Run the following command to check which drivers are in use:

lshw -C display

or

glxinfo | grep "OpenGL renderer"

Ensure the proper drivers are installed (for example, nvidia-driver-### for NVIDIA or amdgpu for AMD).

3. Set the Primary GPU via BIOS

If you want the dedicated GPU to always be the primary one for boot and display:

1. Reboot and enter your BIOS/UEFI (usually by pressing F2, DEL, or ESC).
2. Look for Primary Display, Init Display First, or Graphics Configuration.
3. Select PCIe (for discrete GPU) or iGPU (for integrated graphics).
4. Save and exit.

This method is system-wide and applies before Linux boots.

4. Set the Primary GPU in Xorg (Linux GUI)

If you want to control the primary GPU in your desktop session:

1. Create or edit your Xorg configuration file:

   sudo nano /etc/X11/xorg.conf
   

2. Add a section like:
   

   Section "Device"
       Identifier "NVIDIA Card"
       Driver "nvidia"
       BusID "PCI:1:0:0"
   EndSection
   

   You can find your BusID using:

   lspci | grep -E "VGA|3D"
   

3. Save and reboot.

5. Use Environment Variables (For Specific Apps)

If you only want certain applications to use the dedicated GPU, you can use environment variables:

• For NVIDIA Optimus systems:
  
  

  __NV_PRIME_RENDER_OFFLOAD=1 __GLX_VENDOR_LIBRARY_NAME=nvidia <application>
  

• For AMD switchable graphics:
  
  

  DRI_PRIME=1 <application>
  

This way, you can selectively run apps on your preferred GPU.

6. Verify the Active GPU

To confirm which GPU is active:

nvidia-smi

or

glxinfo | grep "OpenGL renderer"