Clark, who left the game just before the end of the third quarter, had 215 yards on 14-of-23 passing and added 61 yards on the ground. Royster had 141 yards on 17 carries for the Nittany Lions (2-0).
Jordan Norwood led Penn State in receiving with 116 yards and a touchdown.
Lyle Moevao completed 25-of-41 passes for 250 yards but threw two interceptions for the Beavers (0-2). Jacquizz Rodgers accounted for all of Oregon State's scoring, running for 97 yards and two touchdowns.