Average Intelligence Quotient of Computer Scientists?
This is not necessarily the most robust estimation, and is just a blog post (hence I'm not sure it's reliable enough to do anything real with), but here is a posting which uses GRE/SAT scores to estimate IQ across different majors. It puts the average IQ of CS students at ~124.

Another blog post uses GRE/SAT scores again to do the estimate, arriving at 128.5 for CS.

Their original data are from here and here, respectively. I haven't puzzled out yet whether they're using the same base data yet.

Undermining these a little is that there are no supporting statistics (again they are just blog posts, not scientific articles).

I would use these results with a great deal of caution. If nothing else, they appear to be heavily biased to the US setting (simply because of the source data), and given the relatively rapid ups and downs of CS popularity, the data for at least one is somewhat old.