When the new MacBook Pros came out on Tuesday, we pointed out that the laptops could switch between integrated and discrete graphics dynamically a la Nvidia's Optimus. The folks at Ars Technica had a chat with Apple about the subject, and they learned that the Mac maker is using a proprietary but similar switching technology.
Optimus and Apple's scheme differ in two important ways, however. First, whereas Optimus uses profiles to identify applications that require discrete graphics, Ars says the new MacBook Pros call on the discrete GPU anytime an application that uses "advanced graphics frameworks such as OpenGL, Core Graphics, Quartz Composer" opens up. That means Photoshop, too.
The other difference? Ars notes that Optimus leaves the integrated graphics running at all times, powering down only the discrete GPU if it's not needed. Apple's scheme, by contrast, can disable either the integrated or the discrete GPUs depending on which one the system needs.
Optimus or not, the new MacBook Pros definitely do a better job than their predecessors in the graphics switching department. The previous generation required users to head into the System Preferences panel and manually switch back and forth between the integrated GeForce 9400M and discrete GeForce 9600M GT—Apple had left out automatic switching altogether.