Williams finished with 145 yards on 22 carries for the Razorbacks (2-1). He scored on rushes of 6, 13, 12 and 6 yards.
Collins finished with a career-high 212 yards on 27 carries, the longest an 84-yard TD in the fourth quarter to seal the win.
Arkansas quarterback Brandon Allen also added 5-yard touchdown run.
The win gave the Razorbacks back-to-back wins for the first time in more than a year.
Arkansas chewed up more than 13 minutes on back-to-back, 13-play drives in the second half, leaving the defense of the Red Raiders (2-1) spent.
Texas Tech's Davis Webb completed 27 of 45 passes for 252 yards and three touchdowns. He rushed for one TD and threw two interceptions.
Arkansas finished with 438 rushing yards and limited Texas Tech -- which came in averaging 365 yards passing -- to 252 yards through the air.
Arkansas held the ball (40:39) for more than twice the time the Red Raiders had it (19:21), grinding out 31 first downs.
The Razorbacks chewed up almost half of the third quarter on its first drive. On third-and-goal from the 5, Allen dropped back to pass and was being chased by two Texas Tech defenders. Looking downfield, Allen forced two defensive backs to stay on a receiver as he ran into the end zone, extending Arkansas' lead to 35-21.
But, true to form, the up-tempo Red Raiders offense struck quickly. Webb threw his final touchdown on a third-and-12 from the Arkansas 39, hitting Jakeem Grant, in stride, over the middle.
At the start of the fourth quarter, Texas Tech got only its second possession of the final half.
Texas Tech struggled against the run last season and Saturday was a repeat of those problems. In the Red Raiders' five-game losing streak to close the 2013 regular season, they gave up an average of 294 yards rushing.
The Razorbacks, who punted only once all game, took a 28-21 lead into halftime.