Melt the butter in a large pot over medium heat. Add the onion, pepper, and garlic and saute until softened, 5 minutes. Add the flour and stir well, cooking for 1 minute more. Add the broth, milk and the half-and-half. Stir in the cream of chicken soup, salsa, chicken, beans, corn, cumin, onion and garlic powder and fajita seasoning. Continue to simmer over low heat for 15 minutes. Crumble the tortilla chips into individual bowls and top with a ladle of soup. Sprinkle each serving with cheese and add a dollop of sour cream.