Boise State RB Jeremy McNichols soars 70 yards to score his fourth touchdown of the day, increasing the Broncos lead to 28-7 over Oregon State. (0:40)

CORVALLIS, Ore. -- Boise State is 3-0 for the first time since 2011, but walked away from Saturday's 38-24 win over Oregon State with some mixed feelings.

There was the first half, a spectacular showing of offense and defense by the Broncos that led to a 31-7 halftime lead. But for much of the second half, the Broncos' offense was stuck in the mud, and there were special teams that gave up a kickoff return for a touchdown, another long kickoff return that set up another score, as well as an onside kick which the Beavers recovered.

Jeremy McNichols ran for 208 yards and scored four first-half touchdowns in leading the Broncos to their fourth consecutive win over a Pacific-12 Conference team.

"I'm happy that we're undefeated, but I also know we have a lot of work to do," Boise State coach Bryan Harsin said.

The tale of two halves, one where Boise State could do little wrong during the first two quarters, yet seemed stalled during most of the second half, left Harsin to harp on a single word.

"Consistency has got to be there. That's the name of the game when it comes to any phase. We won the game, that's the ultimate goal. But the standard is, you want to play a certain way," Harsin said.

McNichols did most of his damage in the first half, as the junior running back ran for 146 yards and touchdowns of 5, 6 and 70 yards, and caught a 6-yard scoring pass.

Brett Rypien completed 19 of 36 passes for 215 yards and one touchdown for Boise State, which beat Washington State earlier this season.

The Broncos' offense accumulated 512 yards, but only 77 after halftime. Oregon State, held to 67 yards during the first half, finished with 287.

Both teams scored on their opening drive, as Oregon State (1-2) tied the game at 7 on a 14-yard run by Ryan Nall. But the Broncos ran over the Beavers from there, holding OSU to 41 yards on its final six first-half drives, while scoring 24 consecutive points to take a 31-7 halftime lead.

Boise State took a 14-7 lead on a 6-yard run by McNichols with 5:23 left in the first quarter, then sat on that advantage for nearly a quarter before scoring 17 points during the final seven minutes of the first half.

"He was angry out there," Harsin said of McNichols. "On that long run, I didn't see him, he just squirted out of there and he was gone. That's the offensive line, that's the tight end, that's J-Mac. That's what we're capable of doing."

OSU quarterback Darell Garretson was 11 of 16 for 53 yards, but was benched after a half in favor of Conor Blount. The freshman walk-on gave the Beavers a spark, as Oregon State scored 10 third-quarter points to cut the deficit to 31-17.

Darren Lee's 19-yard fumble return for a touchdown by Boise State offset a 99-yard kickoff return by OSU's Victor Bolden during the fourth quarter.

While there were second-half positives, the brief comeback was of small consolation to OSU running back Ryan Nall, who ran for 66 yards and two touchdowns.

"It's pretty simple: execution. We're shooting ourselves in the face with penalties, but we can clean that up in practice. Come Monday, we're going to be ready to roll," Nall said.

It was Boise State's first win in four tries at Oregon State. The Broncos have yet to trail in a game this season.

THE TAKEAWAY

BOISE STATE: The win should put the Broncos in a strong position to crack next week's AP Top 25 and add to their streak of 14 consecutive years where they have spent at least one week in the rankings. Boise State's schedule sets up well for one of its best starts in years, as the Broncos play three of their next four games at home.

Beating back-to-back Pac-12 teams is more mindset than talent, Lee said.

"Everyone we play is talented, everyone's got skill, but at the end of the day, you have to have that mentality. If you're not willing to go out and put it down on the line every play, that's the difference," Lee said.

OREGON STATE: The Beavers, coming off their first win in 11 games last Saturday against Idaho State, now head into Pacific-12 Conference play, where OSU has lost 11 consecutive games. Oregon State will have much to fix on defense, after giving up 435 yards and 21 first downs during the first half to Boise State. The Beavers offense wasn't much help, after managing just 41 yards on their final six drives of the first half.

"It was an absolute beat down in the first half. The kids fought and battled back and did some good things. But you cannot trick yourself into wins against good teams. We have to be able to execute, sustain tempo and sustain drives," Oregon State coach Gary Andersen said.

NO QUARTERBACK CONTROVERSY

Garretson left the game after the first half because Andersen said he wasn't 100 percent due to a lingering foot injury. While Blount had some moments during his college debut, completing 11 of 18 passes for 138 yards, Andersen said when Garretson is physically sound, he'll start for the Beavers.

"Conor can bring some things to the offense with his legs. He did some nice things. I'm not afraid to give freshmen an opportunity," Andersen said. "But when Darrel is healthy, he's the starting quarterback. There's no debate about that."

UP NEXT

BOISE STATE: The Broncos open Mountain West Conference play at home against Utah State next Saturday. Last year, Utah State beat Boise State 52-26, the Broncos' most one-sided MWC loss in school history.

OREGON STATE: The Beavers hit the road for their Pacific-12 Conference opener at Colorado next Saturday. The Buffaloes opened league play Saturday at Oregon.