Seeing as you overclock, your opinion of power efficiency is somewhat hyprocritical. And at that - deeming hardware as being superior BECAUSE of power efficiency is also very subjective. For many, price is the most important. For others, it's the raw performance. I'm assuming you've never dealt with mainframes before because efficiency is hardly a factor depending on what company you're looking at. And like I said, if the drivers are improved well enough, you can involve less transistors, less memory, lower clock rates, and therefore more efficiency (in both a TDP and calculation perspective). Anyway, Nvidia has only started getting noticeably more efficient starting with their 700 series. I think I recall their 600 series also being more efficient but not enough to put AMD at a serious disadvantage.