I have a mac pro 1,1 that I got 10.11.6 running on. It runs great except it has numerous graphical problems cause its an old ati x1900 xt. I have a 750 ti lying around that I figured should run it well but I can't get anything to appear on screen. I installed the nvidia web driver 346.03.15f15-2 because I am on build (15G31). I see the nvidia options in system preferences but when I take out the ati and swap it with the 750 ti I get no picture even after waiting for 7+ min cause I no that the boot logo won't work. any recommendations?