Nvidia Optimus Switchable Notebook Graphics

Ideally, a hybrid graphics subsystem should deliver power on demand automatically and without pause or restriction, which is what Nvidia claims it's achieved with its next generation of switchable graphics, dubbed Optimus.

To understand what makes Optimus unique, we have to dig a little deeper into how current switchable graphics implementations work. On the hardware front, such systems are equipped with an integrated graphics processor (or IGP) in the chipset or CPU, along with a discrete GPU.

The GPU hooks into the system via PCI Express, and it also must be connected to the display outputs, which are shared with the IGP. Sharing is facilitated by high-performance hardware multiplexers, otherwise known as muxes, that feature inputs for each graphics adapter, a single output, and a control line that tells the multiplexer which input to pass through to the display. TechReport