I had a look at your uploaded ACPI tables. They are looking so far fine, because there is nothing about IGPU. You could try to insert in your PEG0/GFX0 a DSM method following this guide: http://rampagedev.wo...rd-into-a-dsdt/ In any case you have also to add the DTGP method patch from DSDT Editor or MacIasl. If you are booting with the edited DSDT.aml GraphicsEnabler has to be deactivated.
Can you please upload an Ioreg gethered by IORegestryExplorer app vers 2,1 without the patched DSDT, and if the DSDT is partial working one after booting with the edited DSDT?
Do you get an external display working?
Well, following that guide is just an impossible. Use DSDT editor to take a look into the dsdt I posted above. The graphics card is atached to PEG0. You will see about 2000 lines of code inside PEG0 beeing GFX0 a monster device with a lot of devices inside. Where to put the fcking code?? You can't just replace the whole GFX0 cause it will gives you about 40 errors and you will not be able to compile the dsdt!!