I KNOW you should have to do this with Nvidia...but I swear I had to do it once when I added a 2nd 570. Plug both cards into a monitor or use a dummy plug. Yeah, yeah, I know, but humor me. It sounds like you covered all the other bases. I came in late on this so sorry if I missed it..you did extend the monitor onto the 430? Sorry if everyone thinks I'm crazy, but this truly worked for me once. I haven't had to do it since. What do you have to lose, but a couple of minutes.