Yeah, bigcyco1 has a point. Nvidia has been shutting down overvolting and proper overclocking for a while now. Their GPU boost isn't robust enough and holds back real overclocking. They've also been getting many reviewers to spread FUD with highly biased reviews such as having them use cherry picked cards, improper driver versions for AMD cards, poor game selection, and ridiculous game settings.
Don't let that stop you from getting what you want, I'd recommend a Nvidia card if I feel that it's the best solution in a given situation, but it is something to think about.