Enable CUDA for Adobe Mercury Engine on unsupported cards? http://bit.ly/92VapW
The fact that Adobe has made this as easy as it is – by simply editing an entry in a text file – suggests they don’t really oppose users doing this on unsupported cards. It’s my understanding that Adobe have supported a relatively small number of CUDA-capable cards so they could be thoroughly tested and to have fewer variables during development. Not sure how you do this on a Mac though.
Remember this is UNSUPPORTED. You are on your own with problems! And you can’t go blaming Adobe for any crashing or other problems on an unsupported configuration. But you can test, and if there are problems, just reverse the change to the text file.