Only time it does change is when I unplug it and it goes to battery mode and activates intelligent display. It shows the setting bar goes up and down, but it dosent change. All adjust setting don't work, ive tried manual and keyboard. So it's not any hardware issue but driver, completely driver Ive scoured the community, tried every setting and driver update, nothing works. Windows 8.1 controls brightness with Optimus enabled and 2 external monitors. I used VIDEO_DRVR_WIN_R307994, which is 8. I went to Dell's driver page for M6600 and looked previous versions of Intel video driver. Home Brightness not working Windows 8.1 Dell
