NVIDIA released a whitepaper that claims multi-core chips can significantly reduce power consumption of mobile devices:
To demonstrate how such a seemingly contradictory stance - adding additional cores resulting in lower power usage - is possible, Nvidia takes the example of a pair of identical mobile devices: one runs a single-core ARM Cortex-A9 chip, while the other features a dual-core ARM Cortex-A9 chip. In both cases, the processors are identical in specification aside from the number of processing cores.
In the paper, Nvidia argues that under a complex workload - running Internet radio, web browsing, and playing Flash content - the single-core chip will run at 100 percent utilisation and have to run at the maximum frequency of 1GHz while drawing 1.1V. Nvidia rates the power draw of the chip as P.
For the same workload on the dual-core CPU, however, the tasks can be shared, leaving each core at 50 percent utilisation. Because the CPU isn't maxed out, it can be run at the slower speed of 550MHz to achieve the same workload - meaning a drop in voltage to 0.8V.
Overall, Nvidia claims, the dual-core processor has a power draw under the same workload of 0.6P - or a 40 percent saving over a single-core chip.