Apple's top end MacBook Pro comes with both Intel and Radeon. Are both used simultaneously?
- The weak one is used to preserve battery.
- The stronger one is used for performance.
Use gfxCardStatus to control this behavior, or let OS X do it itself:
Depends on the situation: The Intel is used for Desktop purposes for energy purposes while the Radeon is used for Graphics and Games for performance purposes. They aren't used simultaneous like SLI...
When you need more performance for things like playing 3D games, editing HD video, or even running CAD software, the 15- and 17-inch MacBook Pro models automatically switch to discrete AMD Radeon graphics that let you see more frames per second and experience better responsiveness.
Dependent on your OS, you can switch the behavior.