Does a tablet really need eight cores?

The core wars have reached a détente on the PC, but mobile is another matter. Some smartphones and tablets are already packing four cores, but chipmakers apparently aren’t stopping there.


The core wars have reached a détente on the PC with most mainstream laptops still relying on dual-core processors. But mobile is another matter. Some high-end smartphones and tablets are already packing four cores, but chipmakers apparently aren’t stopping there.

MediaTek, a Taiwan-based company which has recently grown to become one of the world's largest mobile chip suppliers, is working on an eight-core processor, according to local reports. The MT6599, will supposedly be manufactured by TSMC on an advanced 28nm process and will first appear in a ZTE smartphone in the second half of 2013. That would be a big leap for MediaTek; currently its most advanced chip is the MT6577, a dual-core (1GHz Cortex-A9) processor designed for sub-$200 Android 4.0 smartphones. A quad-core and/or eight-core processor would presumably help MediaTek get into high-end devices including tablets.

Meanwhile Samsung is expected to present details of its own eight-core system-on-chip (SoC) at a chip conference early next year. The SoC reportedly includes two 28nm quad-core clusters, a high-performance one based on the Cortex-A15 and a low-power one based on the Cortex-A7. This seems more feasible--Samsung has been expected to be one of the first to release a chip based on this ARM big-LITLE architecture and it already supplies a quad-core Cortex-A9, the Exynos 4, . (At the same conference, China's Longsoon will unveil its eight-core Godson-3B1500, manufactured on a 32nm process and based on the MIPS architecture, but this is designed for PCs and servers.)

By turning off power-hungry cores when they aren’t needed, technologies such as the companion core in Nvidia's Tegra quad-core and ARM's big.LITTLE will make multi-core work better in mobile devices. But it still isn’t clear that tablets, or even PCs, really need so many CPU cores, or that the software is ready to take advantage of it. After all the fourth-generation iPad's A6X--one of the most powerful mobile processors around--has only a dual-core processor (Apple instead devoted most of the die to graphics). Intel is still shipping single-core Atoms for smartphones and dual-cores for Windows 8 tablets (there are rumors that it will stick with its 22nm dual-cores through all of next year), though this is a different architecture.

Of course, lots of people said the same thing about quad-core mobile processors a year ago, and today there are loads of devices using Qualcomm's Snapdragon S4 Pro, Samsung's Exynos 4 Quad and Tegra 3 (including the Microsoft Surface tablets). I'm still not sure eight full-power cores makes much sense, but by this time next year I wouldn’t be surprised to see lots of "heterogeneous" chips that have a powerful quad-core CPU plus one or two lightweight cores for basic tasks.