Use the DualLink version if your monitor supports a resolution higher than 1366x768. I have only tested it on a laptop, so I don't know if it works on an external monitor.
I've made a commandline tool for patching, so you can try different options, you can also choose the output (LVDS, VGA, DP). Please, carefully read the included README file before using.
THE FOLLOWING ARE NOT NECESSARY:
- "GraphicsEnabler" boot option
- "Graphics Mode" boot option
Also, it does not matter which smbios.plist you are using.
DO NOT MIX DIFFERENT KEXTS FROM DIFFERENT VERSIONS OF OS X!
AppleIntelHDGraphicsFB is responsible for setting up the framebuffer, thus providing the ability to switch resolutions. The other AppleIntelHDGraphics* kexts provide hardware acceleration (QE/CI/OpenGL/Video playback). So, if using the FB kext on it's own works (switching resolutions but no QE/CI), while using it with the others does not, means there's an incompatibility between the kexts you are using.
Please use this tool instead of the kexts I've uploaded here.