From Linux 3D
The nvidia-settings utility is a GPL tool for configuring the NVIDIA Linux graphics driver. It operates by communicating with the NVIDIA X driver, querying and updating state as appropriate. This communication is done with the NV-CONTROL X extension.
Values such as brightness and gamma, XVideo attributes, temperature, and OpenGL settings can be queried and configured via nvidia-settings.
nvidia-settings is included in recent driver packages. Just type:
|Launching the application|
in a shell and you will get a GUI looking like this: