If you have a MacBook Pro with a dual GPU, gfxCardStatus is a handy tool that enables you to quickly see which of them is in use and also to switch between them at will. Used as an information tool, gfxCardStatus is incredibly unobtrusive, but in addition to letting you know which GPU is in use, you are also given the option of manually switching.
One of two icons appears in the menu bar indicating whether you are using the integrated or discrete GPU – expect to see an i or a d accordingly.Should you find that these small icons are not obvious enough for you, there’s support for Growl notifications so you can be alerted when GPU switching takes place.
Manual switching is a great feature of the app, and it is something that can be done on the fly without the need for a restart or log out. If you want to save a little battery when you are away from a power source, you might want to switch to the integrated GPU, while if you want to ensure that you are getting the best graphical performance, switching to the discrete GPU is just a couple of clicks away.
The app can be used on MacBook Pro 2008 onwards, but the big news in the latest version of the program is the addition of support for the retina display of newer MacBook Pros. gfxCardStatus is useful for the switching abilities it provides you with, but it can also be helpful for determining which of the apps you are running is causing your MacBook Pro to switch GPUs and override the setting if you disagree.