News is still coming out about the surprise that Apple’s switching-graphics technology is in fact not NVidia Optimus but a wholly Apple-grown technology. Ars Technica got some info from Apple about the technology on how exactly it differs, and why they consider it superior:
Apple’s approach in the new 15″ and 17″ MacBook Pros differs from Optimus in two key ways. The first is that the switching is all handled automatically by Mac OS X without any user intervention (though there is actually a System Preference to deactivate it, if you choose). Apps that use advanced graphics frameworks such as OpenGL, Core Graphics, Quartz Composer or others will cause the OS to trigger the discrete GPU. So, when you are reading or writing Mail, or editing an Excel spreadsheet, Mac OS X will simply use the integrated Intel HD graphics. If you fire up Aperture or Photoshop, Mac OS X kicks on the NVIDIA GeForce GT 330M.
The second way that it differs from Optimus is that the integrated graphics are powered down when the discrete GPU is active. This saves even more power than Optimus does, leading to a stated battery life as long as nine hours.
One interesting detail I had not thought of before is that in Optimus, when the Discrete GPU is enabled, the integrated GPU is still powered up and in fact being used, the framebuffer is simply being ignored. This means when you are using the discrete (eg. Fast) graphics, you wind up communicating to both GPU’s simultaneously, wasting (albeit a tiny amount) of power and adding a lot of extra communication to the system bus.
