How can I get my GTX970 graphics card to work

I have two graphics cards, one is GTX970 and the other is Core Graphics card.

How do I configure parameters for the conf file?

If I open these two rows ：

nvidia-driver=true

nvidia-prime=true

I play the PS2 God of War 2 is very stuck, drop the frame seriously, I feel the independent video card does not work

How can I get my GTX970 graphics card to work ?? Thanks

Check if tour card shown in settings - information section