Boil cubed potatoes until tender. Drain and let cool. When cool, place in a large bowl. Add the chopped onion and dill pickle relish to the potatoes.
Separate the boiled eggs yolks from the white. Chop up the egg whites and place in with the potatoes. Place the boiled egg yolks in a medium size bowl and mash them with a fork until fine.
Add the cup of mayo to the bowl with the egg yolks. Next, add the ranch dressing powder to the bowl. I recommend a small hand mixer or a small hand blender to mix the powder, mayo and egg yolks. If it is too thick, I add a little dill pickle juice. Mix until creamy. Add to the large bowl of potatoes, onions, and dill pickle relish and mix well.
Place in a covered dish and put in the fridge. Serve when chilled.