I had an unhealthy obsession with IQ testing. A phase long ago. I remember reading that the average Harvard IQ tested at 130 and the other Ivies in the mid-120s. You can guess based on SAT figures, noting that extracurricular factors (paradoxically) decrease the IQ/SAT correlation (people who beat a top school's extracurricular game are more likely than average to have prepped for SATs and have scores that overstate their IQs). So a 1500 average SAT (out of 1600) ends up mapping to a group average IQ around 130, even though a typical individual with a 1500 SAT is probably around 140 IQ.

These numbers fluctuate and it's quite possible that the increasing usage of socioeconomic/extracurricular criteria has decreased the gap.