Hi marxx.

Will you post your full system specs, mobo, everything?

From my experience, dual display option was working flawlessly. I am using (for everyday work) my Sony monitor on DVI, on my 8600GT. I've been using second monitor for some time which was Sony trinitron vga monitor via dvi->vga and dual display was just great. I also tried with second monitor but this time it was also a digital one, so both via DVI. Everything is fine, so no problems with dual displays on OSX. I used efi string with stock drivers back then, now it runs off dsdt but it is just the same.

What i can tell you at this point is to try with efi string first. Make a proper efi string. I suspect on nvcap, so try to find a proper nvcap for your gfx card (there are nvcap tools for osx). Pay attention on this, your primary monitor should be connected to first dvi connector, DVI-1 (it should be first from the left, on rearview, check it out for your card) it is very important step, no matter if the monitor is connected via dvi adapter or it has a straight dvi connection. And if nvcap was correct then you should not have any problems attaching secondary monitor and using dual display view. I hope it will help you out, and other guys, also. 7900 is a great video card, not sure if it works with vanilla drivers, i think it does.

Stay safe,
Regards!

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