http://www.google.co.uk/search?hl=en...erheating&meta=
6600gts are well known for overheating
, and simlpy putting ur hand to the card to test is not gonna tell u anything, what ur feeling is most likely the heatsink which is sitting on the gpu which has a fan blowing onto it and keeping it cool, so its not going to be as hot as the core this however doesnt mean the gpu is getting equally cooled.
what temps does ur drivers controlls say the gpu is at?