The x86 Power Myth Busted: In-Depth Clover Trail Power Analysis
by Anand Lal Shimpi on December 24, 2012 5:00 PM ESTFinal Words
Ultimately I don't know that this data really changes what we already knew about Clover Trail: it is a more power efficient platform than NVIDIA's Tegra 3. I summed up the power consumption advantage in the table below (I left out the GPU numbers since I'm not totally clear with what NVIDIA attaches to the GPU power rail on Tegra 3):
| Power Consumption Comparison | ||||||||
| Surface RT | W510 | Surface RT (CPU) | W510 (CPU) | |||||
| Idle | 3.182W | 2.474W | 70.2mW | 36.4mW | ||||
| Cold Boot | 5.358W | 3.280W | 800mW | 216mW | ||||
| SunSpider 0.9.1 | 4.775W | 3.704W | 722mW | 520mW | ||||
| Kraken | 4.738W | 3.582W | 829mW | 564mW | ||||
| RIABench | 3.962W | 3.294W | 379mW | 261mW | ||||
| WebXPRT | 4.617W | 3.225W | 663mW | 412mW | ||||
| TouchXPRT (Photo Enhance) | 4.789W | 3.793W | 913mW | 378mW | ||||
| GPU Workload | 5.395W | 3.656W | 1432mW | 488mW | ||||
Across the board Intel manages a huge advantage over NVIDIA's Tegra 3. Again, this shouldn't be a surprise. Intel's 32nm SoC process offers a big advantage over TSMC's 40nm G used for NVIDIA's Cortex A9 cores (the rest of the SoC is built on LP, the whole chip uses TSMC's 40nm LPG), and there are also the architectural advantages that Atom offers over ARM's Cortex A9. As we've mentioned in both our Medfield and Clover Trail reviews: the x86 power myth has been busted. I think it's very telling that Intel didn't show up with an iPad for this comparison, although I will be trying to replicate this setup on my own with an iPad 4 to see if I can't make it happen without breaking too many devices. We've also just now received the first Qualcomm Krait based Windows RT tablets, which will make another interesting comparison point going forward.
Keeping in mind that this isn't Intel's best foot forward either, the coming years ahead should provide for some entertaining competition. In less than a year Intel will be shipping its first 22nm Atom in tablets, while NVIDIA will quickly toss Tegra 3 aside in favor of the Cortex A15 based 28nm Wayne (Tegra 4?) SoC in the first half of next year. Beating up on Surface RT today may be fun for Intel, but next year won't be quite as easy. The big unknown in all of this is of course what happens when Core gets below 10W. Intel already demonstrated Haswell at 8W - it wouldn't be too far fetched to assume that Intel is gunning for Swift/Cortex A15 with a Core based SoC next year.
Here's where it really gets tricky: Intel built the better SoC, but Microsoft built the better device - and that device happens to use Tegra 3. The days of Intel simply building a chip and putting it out in the world are long gone. As it first discovered with Apple, only through a close relationship with the OEM can Intel really deliver a compelling product. When left to their own devices, the OEMs don't always seem to build competitive devices. Even despite Intel's significant involvement in Acer's W510, the tablet showed up with an unusable trackpad, underperforming WiFi and stability issues. Clover Trail has the CPU performance I want from a tablet today, but I want Apple, Google or Microsoft to use it. I do have hope that the other players will wake up and get better, but for next year I feel like the tune won't be any different. Intel needs design wins among the big three to really make an impact in the tablet space.
The good news is Microsoft is already engaged with Surface Pro. It's safe to bet that there will be a Haswell version coming as well. Now Intel just needs an iPad and a Nexus win.
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Veteranv2 - Friday, December 28, 2012 - link
You mean on Win8 right?You take a bloated x86 optimized OS with crappy ARM support and you compare it to the best x86 chip maker.
Great... Happy world you live in.
Braumin - Friday, December 28, 2012 - link
Um, smart ass. Medfield was running Android.And Windows 8/RT is far from bloated. Good try though.
jwcalla - Saturday, December 29, 2012 - link
Unfortunately we can't draw too many conclusions about Win8 vs. RT since we can't look at the code base. Especially for benchmarks like "cold boot". The manner of bringing up devices is likely rather distinct.And, unfortunately, we don't know anything about the compilers used for the software either.
Now a compiler like GCC can give us some broad ideas... we can test and see that, in general, it compiles code to an x86 target more efficiently than to ARM architectures... and this isn't particularly surprising since x86 has years upon years of optimizations built into it (GCC). Not to mention that some software will have better x86 optimizations also (this is typical; developing for ARM does require different software implementation methods for optimizations).
But we don't know much of anything about Windows code or compilers since it's kind of closed up. But, in theory, 8 vs. RT shouldn't be line-by-line identical... or that would be a job poorly done.
We can only draw some non-specific conclusions that the two are in the same field of range, and that's all that matters from a user experience perspective anyway. (Or, at least, this particular x86 implementation vs. that particular ARM implementation are relatively close in terms of performance and power efficiency.)
mrtanner70 - Thursday, December 27, 2012 - link
A little more journalistic push back would go a long way. In Intel's eyes they have co-opted you Anand, it's a clear strategy on their behalf, they know you are influential.A brand new atom should not be solely compared with an aging Tegra. I have no problem with the companion core issue given RT does not use it, but a Krait RT product, or Ipad (despite the o/s issue) would have been a much more apples to apples comparison in terms of chip generation. If this article had included one or both of those in addition to the Tegra3 it would have been vastly more credible.
You have the power to push back for the best comparison YOU, not Intel, can think of.
Braumin - Thursday, December 27, 2012 - link
Brand new Atom and aging Tegra 3? The Atom CPU is the same CPU with minor tweaks that was first introduced 5 YEARS ago.The Tegra 3 is a chip that is barely a year old... and still on sale today.
Anand will test a Krait tablet when they are available. Right now there are none. That alone makes this a fair comparison.
And there will be a new Atom next year. When the Krait comes out on a Windows RT tablet, should we then hold off until the new Atom comes out before we do comparisons, or should we compare PRODUCTS YOU CAN BUY RIGHT NOW? I mean both of these devices are new products in the last two months. How is this not relevant?
I mean seriously. These comments are disgusting I used to think most Anandtech readers were tech savvy, but that's obviously not the case anymore.
jwcalla - Thursday, December 27, 2012 - link
The problem with most hardware sites, this one not excluded, is that they seem to be unconcerned about the software influences on these comparisons.Now I love Anand but he's just as guilty in this point in many of the reviews he posts. He'll have a SunSpider benchmark of this platform vs. that platform and then draw conclusions about the hardware, which you just simply cannot do. Such a benchmark allows you to draw conclusions about the entire system only. Now that's definitely important from the perspective of a product review where, ultimately, only the user experience matters. But you can't draw conclusions about A6X vs. Samsung Dual or whatever based on a benchmark run on completely different software stacks.
Likewise, measuring differences in the cold boot process of Surface RT vs. Surface Pro doesn't really tell us... anything... about the hardware at least. Just a cursory understanding of computers explains to us why that is.
However, the goal of this article is to show that Intel can make a chip that plays in the same ballpark as ARM's Cortex-A9s. I'm not sure that that actually establishes anything significant though, since Intel is clearly the challenger in this market... and showing up isn't enough to get wins -- as Anand points out. But it's also what we already knew: when you scale back performance and simplify the instruction set, you get lower power usage.
kyuu - Thursday, December 27, 2012 - link
I think Win8 vs. WinRT are as close as your going to get software-wise between an ARM-system vs. an x86-system.mrtanner70 - Thursday, December 27, 2012 - link
While the underlying architecture is not new, clover trail absolutely is. It just started showing up in shipping devices. It's a comparison designed to be the most favorable one possible for Intel, and a good journalist would push for the best one period. You have an odd definition of disgusting.jwcalla - Thursday, December 27, 2012 - link
To me these results don't even begin to provide a compelling motivation for Apple or Samsung (e.g.) to drop their own designs (and in the latter case, fabs) for Intel in their products. Why introduce a third-party to your supply chain for what amounts to differences that are almost entirely in the noise? (And can easily be caused by measuring errors, software differences, compiler advantages, etc.)The only real plus that Intel brings to the table is for the Windows folks who are enamored with the idea of running XP apps on their phones. But there aren't enough of these people to turn the tide in a market where ARM clearly has a stronghold.
However, Intel should be successful at stemming any losses in the ultrabook or server markets.
kyuu - Thursday, December 27, 2012 - link
There aren't a whole lot of people who care about running x86 apps on their phone, true. However, there are lot of people who would like to run x86 apps on their tablets.