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How many of the instructions are processed by the external gpu when you have a pc which has

1.Intel GMA

2.Nvidia Optimus (selected)

Does intel cpu try to send some instructions to intel gma and try to process some instructions before sending them to nvidia when you select nvidia gpu as the main graphics processor?

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Your question is a little vague. But @Andre's answer covers it pretty well. Not sure why you put OpenGL and DirectX in the question title. – Marcus Chan Feb 7 '13 at 19:10
up vote 3 down vote accepted

If you activate the dedicated graphics the graphics driver starts to redirect all incomming instructions to the NVidia chip. The computed image data is then written into the memory of the Intel GMA which does nothing else than to take care of the output. It does not render anything at all.

I'm not sure if this satisfies your question. Ask if you wan't to know something more.

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Nvidia Optimus will send graphics to either the onboard GPU, or the Nvidia GPU, not to both. The purpose of Optimus is to allow 2D graphics to be processed on the onboard low power GPU and not run them on the power hungry 3D GPU. This allows the laptop battery life to be extended with minimal performance loss. Individual applications can be assigned to specific GPUs if necessary. Check out this article on Nvidia Optimus.

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