Imagine this, Tegra 2 dual core needs less power than a single core Tegra one especially while idling. We heard this from one of the product managers of Tegra who showed us LG Optimus 2X and the latest dual core Motorola.
Nvidia obviously learned a lot from Tegra one to Tegra 2. Tegra one as most of you know had one serious design win, the Zune HD while the rest of the attempts tanked. Still, this multi-billion adventure made Nvidia think a lot about low power chip development.
Idle power will get better and if you can expect that the dual core phones will have a very similar power requirements as the current single cores. Naturally these mobile cores change the clock according to the load, so a dual-core won’t always have both cores enabled and they won’t run at 1GHz all the time. These days are long gone in the chip industry, as power efficiency is becoming increasingly important in all market segments.
The OS will be able to change the clocks and save a lot of energy. Another thing to have in mind is that a screen on Tablet or a mobile phone's screen uses up almost 70 percent of the battery.
Tegra 2 also plays Full HD with less than 200 milliwatts and just a few years back you needed a proper CPU or discrete graphics to do this.