What chipset saves power?

I believe you're talking about Hybrid Power, an nVidia technology intended to switch the dedicated GPU on only when running intensive 3D apps, while using the integrated GPU for web browsing office, etc. It requires a supported nVidia graphics card as well as motherboard, and seems to be primarily for notebooks.

http://www.nvidia.com/object/hybrid_sli.html

Turns out ATI has a similar thing, they just call it Hybrid Graphics, seems to be supported by both desktop and notebook chips, assuming again that you use appropriate AMD/ATI integrated video and a supported ATI GPU.

http://www.amd.com/us/products/technologies/ati-hybrid-...