Multiple GPUs Configuration

Primary GPU	Secondary GPU(s)
Quadro	Quadro
Quadro	GeForce
Quadro	Tesla
GeForce	GeForce

By default all GPUs present in the system are configured both for processing and graphics (used for display), with the exception of the Tesla devices that are exclusively designed for processing.

Power management considerations

GPU Role Assignment

Primary GPU

The primary GPU (the one driving the displays connected to the system), must be excluded form the CUDA enabled devices. The reason for this is that if the primary device is not excluded, then it will also be used by the various CUDA enabled programs and the device will have to share is resources (memory and computing capabilities) between the display(s) and CUDA programs, resulting in a loss of performance (usually 50%).

Please note that the slowest GPU will always drag down the overall performance. Therefore if the primary GPU is CUDA enabled, the overall processing performance will drop

Secondary GPUs

Secondary GPUs must be set for CUDA processing only and excluded from any graphics processing.

The role assignment is defined in the Nvidia Control Panel in the Manage 3D Settings tab:

1. click on the CUDA-GPUs dropdown list to reveal the available installed GPUs in your system:
   

Remember to only check the devices that are to be used for CUDA programs and exclude the primary GPU (the one that your display is connected to).  

Then in the OpenGL rendering GPU drop down list, select the primary GPU like in the following example:  

This setting is available with a Quadro card or an NVS card only.

Mixing GPU architectures

Performance limiting factors