"Both AMD and NVIDIA have launched Hybrid multi-GPU solutions, which not only boosts performance but also work for saving power. NVIDIA seem to take one step more than AMD though, and go all the way by simply discarding discrete chipsets. According to TGDaily, starting with the nForce 700a series, all future nForce chipsets will have an integrated GPU. The reason is so that you will be able to access the HybridPower feature, which lets you minimize the power consumption of your discrete graphics card.
This means that you would connect your monitor to the motherboard, instead of your graphics cards, and that the GPU of the discrete graphics cards would remain dormant until you start an applications, I.e. a game of your liking, and the discrete graphics would kick in and supply the IGP (Integrated Graphics Processor) with more 3D rendering power. Up to four discrete graphics cards could be used in this way. "