We've been working with Intel to quantify the power that CPU cores, graphics engines, memory controllers, and LCD screens consume in specific and well-defined workloads. Intel's motivation is clear: it wants to (and has, we believe) shown that its x86 ISA competes readily against ARM-based devices when it comes to efficiency. And that's on a 32 nm process, even.
Our interest is a little more general, but no less intense. We want to be able to show how much power a given platform consumes when its idle, when it's juggling content consumption, and when it's gaming to show you that the tasks you perform on your tablet greatly influence how much battery life you can expect from it.
Now, on a Windows RT- or Windows 8-based setup, we're able to extend the desktop to an external display, shut off the tablet's screen, and measure power use without the LCD's impact, isolating the platform itself. But Android doesn't give us that flexibility. So, we either have to generate our numbers for the whole tablet, display included, or completely instrument the hardware and hook up leads to the right places, which we're still exploring. For now, these results are for complete tablet solutions.
In our Web browsing benchmark, which includes MP3 playback and a 200-nit calibrated display, the Nexus 10 exhibits the highest power use, confirming suspicions that Cortex-A15 is going to be more power-hungry than the -A9s in Nvidia's Tegra 3 under load. Qualcomm's Krait-based solution is the best-looking in this test, though we have to consider that we're not just looking at the SoC's performance.
At the same time, we know from Samsung ATIV Tab Review: A Tablet To Hold Your Breath For? that the APQ8060A demonstrates crazy-low power use when we bypass the ATIV Tab's display. That makes its commanding first-place finish in the video playback workload even more impressive. In contrast, the Nexus 10 uses slightly more power than Microsoft's Surface, but less than the Atom-based ATIV Smart PC 500T.
An easier workload gives the Nexus 10 an unfair advantage in this break-out of device power consumption in Riptide GP. Really, though, the only stand-out is Microsoft's Tegra 3-powered Surface, which uses quite a bit more power while it renders an enhanced version of the game.