In a large pot, add potatoes and water to cover. Bring to a boil and cook until fork tender. Drain and cool. Peel cooked potatoes and cut into small chunks. Put in a very large serving bowl or container. Peel and finely chop hard boiled eggs and add to bowl. Add mayonnaise, green onions, celery, mustard, white pepper and salt. Mix until just combined. Cover and chill in the refrigerator for 3 hours before serving.