I was investigating a long standing niggle with my MacBook Pro today and finally came across the source of the problem: automatic graphics switching. My specific problem was that when I logged out, the display resolution would drop and even after logging back in I couldn’t restore the resolution. The only solution at that point was to restart the machine.
Or to never log out 🙂
A bit of hunting took my to this thread https://discussions.apple.com/thread/2773585?start=0&tstart=0 which confirmed it wasn’t just me and pointed out the switchable graphics as the source of the problem. The simplest solution was to simply go to System Preferences->Energy Saver and switch off Automatic graphics switching. A better solution was to download gfxCardStatus and gain control of which GPU is used.
This then led on to the observation that my MacBook Pro was using the discrete GPU all the time. gfxCardStatus shows which GPU (integrated or discrete) is in use and the programs running that force the use of the discrete GPU. Taking a look at the list I saw that Skype and Outlook were the culprits. This is irritating as it hits battery life and is rather pointless. Perhaps Skype has a claim to need the power of a discrete GPU while in video calls but Outlook has no excuse, especially as Word and Excel do not force the discrete GPU to be used.
A quick tweak with gfxCardStatus to force only the integrated graphics to be used revealed that Skype and Outlook run just fine in that mode. Additionally, DVDs, Flash video and other media all play smoothly with the integrated graphics. As a bonus my battery life jumped by 50% or more. Integrated graphics seem quite sufficient.
So here’s my tip: download gfxCardStatus, force integrated graphics and say goodbye to display resolutions changes when logging out and hello to longer battery life. Until you run a truly graphically intensive application that is……