Cox accepted a football scholarship from North Dakota State University. As a redshirt freshman, he was converted into a linebacker. He appeared in all 15 games with 8 starts, registering 75 tackles (led the team), 13 tackles for loss (led the team), 4.5 sacks, 6 quarterback hurries, 3 pass breakups and 3 fumble recoveries. In the sixth game against Youngstown State University, he replaced an injured Chris Board and had 3 sacks. He made 13 tackles (7 solo) in the semifinal 55–13 win over Sam Houston State University. He was named second-team All-MVFC and the conference Newcomer of the Year.
