Marks scored 22 of his 27 in the second half and the Broncos (21-9, 9-7 Mountain West) held off a comeback attempt by the San Diego State to earn a split of the season series.
The teams will play Wednesday in a conference tournament quarterfinal in Las Vegas.
Marks grabbed nine rebounds and blocked a San Diego State layup attempt in the final minute to help Boise State hang for the victory. The Aztecs, which trailed by as many as 15 points in the second half, had pulled within 66-63 with 26 seconds left on a 3-pointer by Chase Tapley, who had 17.
ESPN's Dan Dakich joins The Paul Finebaum Show to discuss the SEC's presence in the NBA Draft.
Ted Kapita was the top-rated recruit from West Virginia in the class of 2015 and recently played at DME Academy in Florida.
With the Suns drafting Tyler Ulis, they now have five guards on their roster who attended Kentucky.