Power Consumption and Closing Thoughts

The performance story is interesting but kind of one sided: the Core M 5Y70 is slower than the Core i5-4200U in most of our testing, especially for anything that is using multiple threads. This is not a totally unexpected result though; Intel has been telling us for months that they were targeting performance "near" that of current Ultrabooks with this new CPU.

Luckily for Intel, success in this field is about much more than just benchmarks. Power consumption and efficiency are as much of the story as any of it.

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These Wi-Fi web browsing battery life numbers were run on the Yoga 3 Pro and the Yoga 2 Pro from Lenovo, the same systems used in our benchmarks on the previous pages. The Yoga 3 Pro with the Core M 5Y70 is able to pull out a result that is 8% longer than the Core i5-4200U. That's great and all, but is made even more impressive when you learn that the Yoga 3 Pro has a 22% smaller battery in it! Lenovo shipped the latest Yoga machine with a 44 Whr battery compared to the 54 Whr battery found in last years Yoga 2 Pro.

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The result is the calculated power consumption for the entire system (including processor, screen and other components) seen above. The Core M 5Y70 was able to run at nearly 3 watts less power throughout our Wi-Fi battery testing; that's a difference of 33%. And while we know that not all of that is directly related to the Broadwell architecture, Intel has been making tweaks to the entire Core M platform from the beginning, targeting this exact result.

Though we are saving the full Yoga 3 Pro review for another time, it should be noted that this ability to maintain (or even extend battery life) while using a smaller battery and fewer components (like fans) allowed Lenovo to build a machine that is noticeably thinner and lighter than the previous generation.

Closing Thoughts

It would be easy to look at the Core M 5Y70 processor and come away disappointed. Here's Intel, the biggest microprocessor company in the world, releasing a new generation of products that is actually a step backward in performance compared to Haswell. But that view of the situation is incredibly narrow. Yes, in most of our benchmarks. the Core M 5Y70 is slower than the Core i5-4200U, especially when you look at heavily threaded applications like media transcoding. In several single-threaded workloads, CineBench and 7-Zip for example, the performance of the Core M 5Y70 is right on par with the Haswell generation of CPUs with a significantly higher TDP.

That alone is worth noting. Broadwell-Y has a TDP of just 4.5 watts and is able to match performance of the Haswell-ULT with a TDP of 15 watts in some cases. The Broadwell architecture will be more than capable of outperforming Haswell when we see matched-TDP parts on the market, but for now, Intel depends on incredibly high Turbo Boost clocks, in short bursts, to keep the experience of using a 4.5 watt variant enjoyable. Enjoyable enough that you won't realize you are using a processor with TDP levels typical of small Android and Windows tablets.

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This kind of SoC and platform enables new form factors and designs that we just have not seen capable of running Windows and typical PC applications. The Yoga 3 Pro is just the first example of it, and it would be fair to call it a very modest change over previous designs. It's thinner and lighter, but keeps most of the same feature set and design ideals of previous Yoga notebooks. I imagine true "tablet" designs will become drastically improved when migrated from Bay Trail to Broadwell, should companies like Lenovo choose to go that route. I would also like to see notebooks with much larger batteries, something like the 80-90 Whr options seen in more traditional ThinkPads, to enable TRUE all-day battery life.

Users that are very hard on their notebooks, doing tasks that might not be "standard" by definition, could run into some performance issues with the Core M 5Y70. If you often have 20-30 tabs open, running Photoshop, a word processor, do minor video editing or similar scenarios, you might want to wait and see what Intel has planned for the 10-15 watt variants of Broadwell later in 2015. The Lenovo Yoga 3 Pro and the Core M processor will absolutely be able to handle this setup, but if you are moving to it from a higher performance Ivy Bridge or Haswell system, you might notice the step backward every once in a while.

Intel promised the market that it would have 14nm Broadwell processors on shelves in Q4 of 2014 and the Core M 5Y70 is here to prove them right. Though not a performance powerhouse, I think the first taste of Broadwell is delectable and provides vendors with an amazing option that balances the performance of Haswell with the power efficiency of Bay Trail and the Atom lineup. I can't wait to see more.

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