There was a study, some 30 years ago or more, that found that visual memory (not IQ) was the only attribute that had a significant correlation with success in chess. I wish I could cite you the reference, but I am operating from memory, and I am not a reference library. Add to that the problem that it is unclear just what IQ is or whether any measure of it can be valid and reliable. See Gould’s The Mismeasure of Man.