Guys, keep in mind that the difference isn't just straight power improvement...You are also paying for more reliability under stress, increased refresh rates, a faster clock most of the time, faster bandwidth, lower temperatures...so on. The actual amount of VRAM does play a factor into this, and is a good place to start looking but a good thing to remember is that, barring some known issue, a newer model(ie 770 > 680) is going to just be better put together than the older versions. Also, usually, when they jump from say the 600 series to the 700 series they change something large, like reconfigure the boards or replace some pinnacle component for better optimization. Careful with the thought process that 680 == 770 cause they are NOT the same thing, they just are similar in the basics.