R5 240?

I just got my first Hackintosh running on Dell Optiplex (Forgot a number but it's SFF). Everything working fine as it's should except one thing and it's my R5 240 that's in the tower. I can't change to another GPU that's common because of the form factor that my Optiplex comes with. So, does anybody know how to get it's working? I was using Olarila High Sierra.

Thanks if help is possible.