Cook linguine according to package directions; drain. Meanwhile, in a large bowl, combine the ham, soup, 2 cups cheese, sour cream, onion, green pepper and butter. Add the pasta; toss to coat., Transfer to a greased 13x9-in. baking dish. Cover and bake at 350° for 35 minutes. Uncover; sprinkle with remaining cheese. Bake until cheese is melted, 15-20 minutes longer.