Trim the prime rib roast of excess fat and any connective tissue. Lightly score the entire roast in a criss-cross pattern (about 1/8 inch deep).
Preheat the oven to 400 degrees F (200 degrees C). In a small bowl, mix together the kosher salt, garlic powder, and black pepper. Rub the mixture into the roast until it develops a crust. Really pack it on.
Place the roast into a roasting pan, and pour water into the bottom of the pan to 1/2 inch deep. Cover the roast with a lid or aluminum foil.
Roast in the oven for about 1 1/2 to 2 hours, then check the internal temperature using a meat thermometer. The internal temperature should be at least 145 degrees F (63 degrees C). Hold the roast in an oven at 200 degrees F (110 degrees C) until ready to carve.
Let stand for a few minutes before carving if not holding. Put on your silly white hat, set up the buffet carving station, and watch the hungry people line up!
