Bring a large pot of lightly salted water to a boil. Add whole potatoes, and cook until tender, 15 to 20 minutes. Drain, run under cold water to cool, and chop into 1 inch cubes. Transfer to a large serving bowl, and refrigerate until completely chilled, about 2 hours.
In a small bowl, stir together the ranch dressing mix, mayonnaise and green onion. Cover, and refrigerate for about 2 hours to blend flavors.
Wrap bacon in paper towels and place on a plate. Cook in the microwave until crisp, about 15 minutes depending on the power of your microwave. Cool.
Stir the mayonnaise mixture into the bowl of potatoes. Crumble bacon into the bowl, and stir to distribute. Serve.
