Devon Collier led the Beavers (3-1) with 20 points and 7 rebounds, while Angus Brandt had 19 points and seven boards.
Oregon State shot 64 percent from the field.
SIU-Edwardsville (1-6) was led by Maurice Wiltz, who had 16 points. Donivine Stewart added 13 points, seven rebounds and four assists for the Cougars. Stewart came into the game leading the Cougars in scoring at 14.2 points per game.
The Beavers started the game on a 13-3 run, with Victor Robbins scoring seven of those points. Robbins finished with 12 points.
The Cougars only basket in the first three minutes was on a deep 3-pointer by Stewart with the shot clock winding down.
SIUE shot 39 percent during the first half, during which the Beavers led by as many as 25 points. The half ended with Oregon State up 52-29.
The Cougars only got as close as 16 points during the second half.
The nation's scoring leader coming into the game, the Beavers' Roberto Nelson scored 17 points, 13 points off his season average. He did match a career high with seven assists and was content to distribute the ball in the first half, attempting just three shots and scoring four points.
In just their second season as a fully-certified NCAA Division I program, the Cougars were winless in Portland State Tournament over the weekend, losing the three games by a combined nine points.
SIUE was playing its fourth game in five days.
The Beavers last game was a 79-73 win over Maryland at College Park with President Barack Obama in attendance. Oregon State coach Craig Robinson is Michelle Obama's brother. Oregon State is 4-0 with the president in attendance.
The Beavers next play DePaul on Sunday in Chicago (TV: Fox Sports 1, at 1 p.m. PT)
HOOPS: Beavs crack century mark, now 3-1
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