The Tar Heels have won 21 of 23 meetings since Williams returned to his alma mater in 2003, including all 11 meetings in Chapel Hill. N.C. State hasn't been closer than nine points in the past 10 meetings at the Smith Center.
T.J. Warren scored 21 to lead the Wolfpack, who had won three straight - the past two by a combined six points - to build some momentum.
But N.C. State didn't do much to reverse its long-running struggles in Chapel Hill, missing 10 of 11 shots to open the game and going 10-for-40 (25 percent) in the opening half to trail 40-23. The Tar Heels pushed that margin to 22 points three times - twice with spurts coming after N.C. State had pulled to within 13 - and never let the Wolfpack get the lead to single digits.
The Tar Heels shot just 41 percent and finished with a 52-36 rebounding advantage, including a 22-12 edge on the offensive glass that led to 20 second-chance points - though they blew plenty of in-close looks and finished just 17-for-45 on shots in the paint.
McAdoo had six offensive rebounds, while freshman Kennedy Meeks had five of his 10 rebounds on the offensive glass.
N.C. State shot 65 percent (17-for-26) after halftime to make things more interesting and finished the game at 41 percent, but it never recovered from its bad start that kept Mark Gottfried's Wolfpack in catch-up mode all afternoon. Warren finished 9-for-16 from the field, while Desmond Lee scored all 18 of his points in the second half.
The Wolfpack scored two straight baskets to start the second half only to see the Tar Heels answer with a 9-0 burst - ending with putbacks from McAdoo and Meeks - that pushed UNC to a 49-27 lead with 17:18 left.
Then, after the Wolfpack made another push to get the gap back to 13 again, the Tar Heels put together an 8-0 run and six straight scoring possessions to push the lead back to 22. McDonald ended that run with a 3-pointer, pushing UNC's lead back to 22 at 68-46 with 8:12 left.
Warren's basket with 90 seconds left cut the deficit to 76-66, but the Wolfpack got no closer.