The people with high IQ may vote to further the interests of people with high IQ, effectively oppressing the people with low IQ.
What would that be? More library funding? NASA? NSF?
This entire idea if IQ or "smart" as somehow better has tried and failed repeatedly in history. There is no benevolent ruler, as they will get displaced in short order.
It stands to reason that the white-collar, high IQ voters would be less concerned with policies which affect manual laborers. These could include workplace safety protections, certification requirements, etc.