Place the cubed potatoes in a large pot, cover with water, and bring to a boil. Cook until the potatoes are fork-tender, then drain and let them cool to room temperature.
In a mixing bowl, stir together the mayonnaise and sour cream until smooth.
Add the cooled potatoes, chopped hard-boiled eggs, crumbled bacon, shredded cheddar cheese, and sliced green onions to the bowl.
Season with salt and black pepper, then fold everything together gently so the potatoes stay in chunks.
Cover and refrigerate for at least 30 minutes before serving to let the flavors blend.