gSwitch
gSwitch lets you set which graphics card your macbook pro can use, mainly to prevent it from using the discrete graphics card when it is simply unnecessary. Why would you want to do that you ask? Well the discrete graphics card uses significantly more power than the integrated one, which can ruin your battery life. There are also problems on some macbooks with glitchy and buggy graphics card drivers that apple still hasn't fixed!
Install
The easiest way to install is to use brew (homebrew required)
brew cask install gswitchOR
You can download the most recent release (click download .zip).
Then after unzipping just move the gSwitch.app file to your applications folder.
OR
You can build from the source.
You must have Carthage installed (homebrew required)
brew update
brew install carthageAnd then in the project folder bootstrap the frameworks:
carthage bootstrapand then build in xcode
Usage
The app is simple to control with integrated only, discrete only, and dynamic switching in the menu.
You can also enable notifications for when your gpu changes (off by default)
You can also launch it from the terminal and set the desired setting using --integrated, --discrete, and --dynamic.
FAQ
Why won't the app start?
You probably need to allow the application to run in Settings -> Security & Privacy
How do I know which gpu is active?
The gear will have a dot in the middle when the discrete gpu is active. Otherwise, it will just look like a gear. The current gpu is also reported in the menu.
Why does the app go back to dynamic switching when a display is plugged in?
Unfortunately your mac is designed such that in order to use an external display, it has to use the discrete graphics card. And since you plugged in the cable I'm assuming you want to use the display. When you unplug the display, if you want to use a different mode, you will have to manually set it (at this time).
What is a dependent process vs a hungry process?
A dependent process is one that is currently using your discrete gpu. A hungry process is one that wants to use the discrete gpu but is not allowed because you have set integrated only. If you change to dynamic switching or discrete only any process that was hungry will become dependent.
How do I disable my discrete GPU?
The short answer: You can't, your macbook was designed to use both, but gSwitch can trick it into using the integrated one most of the time. However gSwitch cannot prevent your discrete gpu from being accessed by the operating system, and it will be accessed for a short period of time when a process requests the use of it. gSwitch just switches back to the integrated one as fast as it can.
The long answer: Ok I lied you technically can but I DO NOT RECOMMEND IT. I know there were alot of problems with the 2012/2013 macbook pro models with GPU's that would start to artifact or even fail entirely and cause the computer to crash when used. The only time I would recommend disabling the discrete gpu is if you are affected by this. However, this procedure is not for the faint of heart and you can brick your computer if you do it wrong! There are also some downsides, like you will never be able to connect an external monitor and you will probably be stuck on an older operating system. Still want to do it? ok.. but, I STILL DONT RECOMMEND THIS AND DONT BLAME ME IF YOU BREAK YOUR COMPUTER https://apple.stackexchange.com/questions/166876/macbook-pro-how-to-disable-discrete-gpu-permanently-from-efi/285896#285896
Legacy
At this time it seems like gSwitch will not work on macbooks older than 2011. It appears that apple has removed the necessary API's from these macbooks on the modern macOS. However there could be other API's that could work, I just can't find any. GPU control with apple is mostly guess work since there isn't any documentation, so, If anyone finds anything let me know here!
Notes
Requires macOS >= 10.12