since upgrading to yosemite i have noticed that on about this mac it is showing intel graphics instead of nvidia. and when i check the nvidia settings in preferences it says the driver is incompatible.
There is a nVidia driver built into Yosemite. It will swap in the nVidia GPU under a heavy graphics load, or when Automatic graphics switching is unchecked under the energy preferences (warning this drains your battery). I assume you mean the CUDA driver.