The more cores the merrier rule also applies to smartphones and other mobile devices.
Today's smartphones have chips inside that can produce output that surpasses that of a Nintendo Wii – which is very impressive for something that fits inside your pocket. But those right now are single-core, and as any computer enthusiast now knows from their desktops and laptops, more cores tend to make for a better computing experience.
The top-end chips inside tablets and smartphones next year will be dual-core, and Nvidia has published a whitepaper on why it will be a great thing not only in terms of performance, but also power consumption.
Essentially, having two cores splitting the work puts less strain on each individual core as compared to having a single core shoulder the entire load. This not only allows for greater performance potential but also a generally lower power draw – provided that both cores aren't under a greater load.
Check out some of Nvidia's charts below for a better idea, and then the full white paper for more details.