Apple’s higher-end MacBook Pro systems come with two graphics cards: an integrated one on the CPU and the other a dedicated graphics processor. While more powerful and useful for image manipulation, design, and gaming, the dedicated GPU requires greater energy and can greatly reduce your battery life when in use.
In most cases, OS X will by default switch between using these two graphics processors, depending on the demands of the system. If you are performing general tasks, then OS X will use the integrated GPU, but if you play a graphics-intensive game, then it will turn on the dedicated GPU and use that instead. This feature allows you to save battery life while optimizing performance; however, there is no option to continually save battery life by only using the internal GPU. Apple does include an option in the Energy Saver system preferences to change the GPU behavior; however, the options here are to automatically switch, or only use the dedicated GPU.
This limitation may be frustrating, especially since with Apple’s MacBook Air and other laptops, the systems only have an integrated GPU and use it at all times. Therefore, even though some applications may demand the use of a dedicated GPU, they can function perfectly fine on the lower-power one, and help you save battery life.
Unfortunately the only way to tackle this problem is to use a third-party utility like gfxCardStatus, which can be used to force the use of the integrated GPU. In most cases this should work just fine; however, even it will have its limitations. In some cases, gfxCardStatus may not be able to force the use of the integrated GPU, and as a result, regardless of whether or not you are using these programs your computer may be using the dedicated GPU and draining your battery power faster, even if you are not actively performing tasks that should be requiring the dedicated GPU.
External displays force dedicated GPU usage
Applications may force dedicated GPU usage
While you might expect design programs and graphically intensive games to draw more GPU power, there are some other less expected ones that will do so. One example of this is Apple’s Chess and Photo Booth programs, which do use graphics acceleration features even though they are not too demanding. You might also find Keynote and other iLife programs (with the exception of iTunes), XQuartz, Grapher, and some third-party programs like Google Sketchup, VLC, Data Rescue, and many others may also force the dedicated GPU to be active even if you have gfxCardStatus running and attempting to force use of the integrated GPU.
Despite this, you can still use gfxCardStatus, as it will indicate which GPU is active, and allow you to better gauge your expected battery life. In addition, gfxCardStatus will list which programs are forcing the use of the dedicated GPU if you try to have the system only use the integrated GPU. Coupling this with the system’s battery menu that, in Mavericks and later, lists the programs using the most energy, you can help identify programs that might be draining your battery.