Most of the evidence is equivocal, as far as I can tell.  Some early studies suggested higher IQ’s, but there was most likely a selection bias in those studies.  Believe me, as a neuropsychologist, this was one of the first things I researched after finding out that our son had SWCAH. 

Extra male hormones in theory might affect intellectual development, although my guess is that any differences between CAH and non-CAH children is significantly outweighed by their similarities (as is the case with almost any attempt to differentiate groups of people).