rendering when connected to multiple displays and/or if using two or more different types of Nvidia GPUs. This does not affect single or multiple displays running on single or multiple GPUs (SLI) under DirectX, which encompasses most games and the Windows Desktop. As such, the setting is largely irrelevant to most users.
If you have a multiple display or mixed-GPU setup, and run OpenGL games or applications, then the available options to consider are Single Display Performance Mode, Multiple Display Performance Mode, and Compatibility Performance Mode. If you have only one display, or are having problems with the other modes, the Single Display Performance Mode option should be used. If you are using multiple displays then select the Multiple Display Performance Mode, but if you experience any issues with particular programs, select the Compatibility Performance Mode.
It is recommended that Multi-Display/Mixed-GPU Acceleration be set to Single Display Performance mode on single display systems, and Multiple Display Performance Mode on multi-display systems, or simply left at its default of Multiple Display Performance Mode on all systems under Global Settings, as it has no impact in most case