Harden made 11-of-17 from the field, hit four 3-pointers and scored 34 points in 39 minutes. Houston has won its two games this season, having played both of them at home.
Howard, who came to Houston during the off-season from the Los Angeles Lakers, claimed 26 rebounds against Charlotte in his debut with the Rockets on Wednesday. He backed up Harden in this game by scoring 13 points and collecting 16 boards.
Jeremy Lin added 14 points for the Rockets, who led by 16 after one period and built the advantage to 21 during the second quarter.