I have a feeling.. the GPU is probably custom. We tried installing the Asus G750JW NVidia 311.59 driver onto my friends MSI GT70 2OC 311.48 but it said it won't work. It works on mine because I have the G750JW.
I saw the G75's card be completely crazy looking for an NVidia 660M I think it was. It doesn't have the same MXM 3.0b standard. I find the placement of the GPU be far right instead of left next to the CPU. I hope they didn't mess up the MXM 3.0b style. I want to be able to go 880M in the future with just a power adapter change.