Heres a little handy app that works quite well. Specific to Macs with Dual Graphics cards, normally the only way to change cards is to log out and log in again, after changing the preference under Power Settings. You have one for Power Saving and one for High Performance graphics.
Cody Krieger (@codykrieger) wrote a handy little App that will let you change Graphic Cards without having to logout, quite handy if you want to just muck about for a bit and then open up Team Fortress 2, or do some Video work.
So I present today gfxCardStatus.
As the Author writes:
gfxCardStatus is a menu bar application for OS X that allows users of dual-GPU 15” and 17” MacBook Pros to view which GPU is in use at a glance, and switch between them on-demand.
Most of the time it spends all its time just in my Task Bar sleeping showing which card I have enabled (i for the power saving low powered card, and d for the high-powered card).
It works quite well, sometimes you request a change and your machine won’t honour it straight away, normally this is down to another application doing something graphics heavy, so locking the control out.
One useful feature built-in is the ability to auto switch the graphics card in use based on the current power source.
Which I don’t personally use, but then I tend to hot swap between on/off PSU far too often.
I’ve a couple of options missing and some different settings available, but it depends on what model of Mac you have and the Graphics Card present in your machine.
All in all its quite a handy little app, and its Free. You can download it from http://codykrieger.com/gfxCardStatus and start using it straight away.