Southwick fired two touchdown passes and Harper added a rushing score on 24 carries as the Broncos (10-2) recorded a third straight triumph.
Matt Miller led the Boise State receiving corps with seven grabs for 127 yards and a touchdown.
Stephfon Jefferson amassed 139 yards and two rushing scores on 28 attempts for the Wolf Pack (7-5).
Cody Fajardo passed for 194 yards and ran for 101 more with a touchdown on 12 carries for Nevada.
2014: The Year in Music [PHOTOS]