1. Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 10 inch tube cake pan.
2. In a large bowl, cream together the butter and sugar until light and fluffy. Stir in the eggs one at a time, beating well with each addition, then stir in the vanilla. Mix in mashed bananas, sour cream and buttermilk. Combine the cake flour, salt, baking soda and baking powder. Stir flour mixture into sugar/banana mixture. Fold in the chocolate chips. Pour batter into prepared pan.
3. Bake in preheated oven for 35 to 45 minutes, or until golden brown and top springs back when touched. Remove from oven and let cool for 15 minutes before removing from pan. Cool completely before slicing.