Place potatoes in lg pot, add water to cover. Bring to a boil. Reduce heat to medium and simmer until tender about 15 mins.
Drain, run under cold water to cool. In lg bowl, whisk together sour cream, mayonnaise, and 1/2 cup chives. When potatoes are cool enough to handle, add to bowl. Stir gently to mix. Season w/ salt and pepper. Garnish w/ remaining chives.