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Getting To The Bottom Of Platform Power

Samsung ATIV Tab Review: A Tablet To Hold Your Breath For?
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Could SoC vendors build higher-performance hardware better able to cut through more taxing tasks? Absolutely. But in this space, power consumption is more important than performance. Even a 1 W difference in total platform power use can mean hours of battery life. That's why you've seen us go into more depth dissecting consumption lately in ARM Vs. x86: The Secret Behind Intel Atom's Efficiency and Update: Intel Expands Our Battery Testing At CES 2013

The results presented in those two links were generated by feeding identical workloads through tablets based on different SoCs, and then recording power figures from physical connections to power planes on the bare circuit boards. Here, we're working backward from our battery life numbers using the following formula: Watts (W) = Battery Capacity (Wh) / Battery Life (in time [h]).

Of course, we're unable to compare Tegra 3 to APQ8060A to Atom Z2760 directly this way, since each tablet uses a different display that also factors into the equation. But we've attempted to create as fair a comparison as possible by calibrating each screen to 200 nits and using the latest firmware/drivers.

Keep in mind, though, that battery life and power consumption comparisons are very situational. In Chris Angelini's story from CES 2013, he pointed out that the workload you apply to each SoC affects power use in a different way. So, the numbers we have here are applicable to the very specific sequence of spending six minutes reading a certain Wikipedia entry, reloading, and listening to constant MP3 audio playback. That's not very intensive. Also, device optimizations are critical. A simple update to the ATIV Smart PC 500T's firmware yielded around 10% greater battery life, for example. Finally, Nvidia points out that features like its PRISM technology also affect battery life, making it doubly important to be totally transparent when we talk about workloads and granular measurements of core, graphics, and display power use. 

We've already established that Intel's x86 ISA indeed holds its own against ARM-based SoCs when it comes to efficiency. Even though these average wattage numbers don't come from a logger hooked up to each tablet's battery, the Qualcomm and Nvidia numbers are still impressively close to what Angelini reported from CES. The ATIV Smart PC 500T sits in the middle of the field, higher than what I might have expected given Chris' measurements. Remember, though, that Intel put a lot of effort into optimizing the Iconia W510 featured in the company's suite. The 500T doesn't seem as aggressively tuned for low power consumption.

With all of that said, we see that the dual-core, 28 nm APQ8060A-equipped ATIV Tab uses less power than the Tegra 3-based Surface, all variables (such as the display) included.

The finishing order of this workload is exactly the same as what Chris measured using logging equipment, though the numbers themselves differ a bit. In both cases, he and I used a H.264-encoded copy of Iron Man. Our ATIV Tab results match up almost identically. The Smart PC 500T uses a little more power than his Iconia W510 (again, expected, given Intel's optimizations to the Acer tablet). And my Surface looks more power-friendly than what he measured by about .17 W.

In both sets of benchmark numbers, Samsung's ATIV Tab uses the least amount of power playing back our movie workload. Given a comparably-sized power source, this should manifest itself on the next page as superior battery life from the Tab as we drain it with Iron Man, looped.

When it comes to gaming, Tegra 3's eight pixel shaders and four vertex shaders can't handle Vector Unit's Riptide GP more efficiently than the Adreno 225 or PowerVR SGX545 engines. What about the games optimizations for Nvidia's SoC? The developer disables detection under Windows RT, so all three architectures are forced to content with the same more-demanding effects. Score a win for Intel on this one. How is this possible?

While we were at CES, however, we met up with Lazslo Kishonti, CEO of Kishonti Informatics and the developer of GLBenchmark. He pointed out that Atom-based tablets running Windows 8 are more likely to deliver different levels of performance. Imagination Technologies writes its own drivers and supplies them to its partners. Because Intel has certain requirements that Imagination is not willing to satisfy, however, Intel writes its own software for the PowerVR core.

Factoring Out The LCD

This analysis thing is like a drug, and we wanted more. So, we thought we'd output to an external display and shut off the tablet's panel, effectively removing it from our power measurements (an exercise only possible under Windows 8 and RT). Although this limits the number of tablets we're able to compare, we really wanted to see how the results would change.

Our setup is pretty basic: we set BrowsingBench to run in battery life mode, which prevents the browser from caching data. Instead of running through as quickly as possible, operations are executed at user-time, in real-world speeds. In addition, the benchmark pauses on sections of a webpage to simulate reading time.

Tablets
Samsung ATIV Tab
(Qualcomm APQ8060)
Samsung ATIV Smart PC 500T
(Intel Atom Z2760)
Microsoft Surface
(Nvidia Tegra 3)
Battery Capacity
30.75 Wh
30.75 Wh
31.5 Wh
Internal Panel
2.75 W
3.84 W
3.31 W
Output to 1080p Monitor
0.77 W
2.79 W
1.58 W
Difference Attributed To Internal Panel
1.98 W
1.05 W
1.73 W


We'd really like to log the power use of BrowsingBench with fully-instrumented tablets to confirm the data in our table. But it looks like bypassing the Tab's 10.1" display sheds nearly 2 W of power consumption, on average, as the benchmark runs, looped. Let's quantify this a little: after two hours of outputting its display signal to an external screen, the ATIV Tab's 30.75 Wh battery only drops 5%. The Surface's larger 31.5 Wh battery drops between 10 and 11% (we ran this three times to be sure).

Samsung's Smart PC 500T remains difficult to explain, as its externally-output power number looks a lot higher than we'd expect.

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  • 0 Hide
    tanjo , January 21, 2013 4:01 AM
    Power consumption graphs says this tablet has Z2760.
  • 0 Hide
    kyuuketsuki , January 21, 2013 4:39 AM
    Quote:
    While we were at CES, however, we met up with Lazslo Kishonti, CEO of Kishonti Informatics and the developer of GLBenchmark. He pointed out that Atom-based tablets running Windows RT are more likely to deliver different levels of performance.

    Er, you mean Atom-based tablets running Windows 8? (Page 6, Paragraph 11)
    Quote:
    Power consumption graphs says this tablet has Z2760.Our setup is pretty basic: we set BrowsingBench to run in battery life mode, which prevents the browser from caching data. Instead of

    Where's the rest of this paragraph? (Page 6, Paragraph 13)
  • 2 Hide
    kyuuketsuki , January 21, 2013 4:43 AM
    Also, I'm not sure what's up with the Futuremark Peacekeeper and Rightware Browsermark results, but we know damn well the Krait S4 in this tab is a better performer in every way to the Tegra 3. Not sure why go with the S4 Play with the dual-core Krait and Adreno 225 instead of an S4 Pro with quad-core Krait and Adreno 320, though, especially in a tablet form-factor.
  • -4 Hide
    mayankleoboy1 , January 21, 2013 6:35 AM
    KyuuketsukiNot sure why go with the S4 Play with the dual-core Krait and Adreno 225 instead of an S4 Pro with quad-core Krait and Adreno 320, though, especially in a tablet form-factor.

    Because Win8 is already a battery hog compared to Android, and adding power hungry cores will make that worse.
    I dont see any issues with S4 pro and Android.
  • 0 Hide
    cangelini , January 21, 2013 9:39 AM
    KyuuketsukiEr, you mean Atom-based tablets running Windows 8? (Page 6, Paragraph 11)Where's the rest of this paragraph? (Page 6, Paragraph 13)

    Fixed!
  • -1 Hide
    dokterprio , January 21, 2013 11:01 AM
    Why there is difference in power usage between ativ tab and ativ smartpc 500t. I think they are the same, except the screen size.
  • 0 Hide
    adamovera , January 21, 2013 11:08 AM
    tanjoPower consumption graphs says this tablet has Z2760.

    Apologies, fixed now.
  • 1 Hide
    adamovera , January 21, 2013 11:13 AM
    dokterprioWhy there is difference in power usage between ativ tab and ativ smartpc 500t. I think they are the same, except the screen size.

    Sorry, we had the charts labelled the same. The ATIV Smart PC 500T has an Atom and runs Windows 8, while the ATIV Tab has an ARM-based chip from Qualcomm and runs Windows RT - they are actually very different devices.
  • 0 Hide
    ojas , January 21, 2013 11:24 AM
    BrowsingBench scores: are the ipads in correct order?
  • 1 Hide
    adamovera , January 21, 2013 11:45 AM
    ojasBrowsingBench scores: are the ipads in correct order?

    Seems to be, I haven't used this benchmark yet myself, and I'd have to check with the author to be sure, but I'd guess that these results are inversely reflecting the resolution of the different iPads.
  • 2 Hide
    Psycomo , January 21, 2013 12:02 PM
    "Can we say we blame Samsung? Hardly. Just imagine answering this one all day long: "So wait, it's Windows, but I can't install Chrome on it? I'm limited to that weak list of apps in the Windows Store? I wish I knew that before I bought this thing!""

    What a load of shite. If you can sell it abroad you can sell it in the US. If that is what they are thinking then they wouldnt be able to release it anywhere.
  • 0 Hide
    damianrobertjones , January 21, 2013 6:06 PM
    So... in 'reality' what resolution is the Rertina iPad running at when compared to screen space and productivity... yep, you can't compare them. Heck, a 1080p screen, for work, on a tablet blows the Retina away. Trouble is... you'll go blind so you might as well increase the DPI.
  • 0 Hide
    back_by_demand , January 21, 2013 9:58 PM
    PsycomoWhat a load of shite. If you can sell it abroad you can sell it in the US. If that is what they are thinking then they wouldnt be able to release it anywhere.

    I think they are passing judgement on typical Joe America here, not the fizzed up techy types (minority) but the dumbass hillbillies (vast majority) that have access to a local Best Buy but are as technically clued up as Amish folk.
  • 0 Hide
    ojas , January 22, 2013 11:24 AM
    adamoveraSeems to be, I haven't used this benchmark yet myself, and I'd have to check with the author to be sure, but I'd guess that these results are inversely reflecting the resolution of the different iPads.

    Ah, that way. But does that mean there was no standard resolution used for testing? But then i guess that wouldn't reflect the "out of the box" experience...
  • 0 Hide
    Anonymous , January 23, 2013 5:24 AM
    It's nice to have Office, but there's just so much else missing.


  • 0 Hide
    halcyon , January 24, 2013 1:32 PM
    Quote:
    Also, you won't be able to buy it in the U.S. for the time being (we're only finding it for sale in the U.K. and Australia).

    I stopped reading right there.
  • 0 Hide
    upgrade_1977 , January 24, 2013 3:19 PM
    No RT for me..
  • 0 Hide
    valuednotoutsourced , January 24, 2013 5:11 PM
    I don't know what Samsung model was reviewed, I was hoping they were reviewing the Samsung ATIV SmartPC model XE700T1C that is available in Canada. The specs for the Canadian model address most of the shortcomings revealed in the review.
    Samsung ATIV SmartPC model XE700T1C
    Chips - Intel® Core™ i5 Processor 3317U (1.70 GHz, 3 MB L3 Cache), Intel HM76, Intel® HD Graphics 4000, 4 GB DDR3 System Memory at 1600 MHz
    11.6" FHD LED Display (1920 x 1080), LCD-Touch Screen, S Pen (with Watcom 1024 Level Pressure Sensitivity Digitizer)
    Ports - Micro HDMI, Micro SD, USB3.0, Headphone out /Mic-in Combo, Dock Port, DC-in
    Bluetooth V4.0, Intel® Centrino® Advanced-N 6235, 2 x 2 802.11b/g/n (up to 300 Mbps), Widi Support
    - Multimedia - HD Audio, SoundAlive™, 1.6 W Stereo Speaker (0.8 W x 2), 2 MP + 5 MP Dual Cam
    - Physical Specification, 304.0 x 189.4 x 11.9 mm (11.97" x 7.46" x 0.47"), 0.88 kg (1.94 lbs)
    - Power - 40 Watt, 4 Cell (49Wh)

    Please review this model
  • 0 Hide
    mas , February 2, 2013 7:25 PM
    So is the goal to simply reproduce a laptop in the form factor of a tablet?
    In that case I already possess a full featured laptop that renders the tablet superfluous.

    On the other hand, if they incorporated full phone capabilities aka the Note2, (especially how about a phone function that includes ALL of the major phone & data carrier bands, making it a true international device?????????

    Also, include multiple user exchangeable micro SDHD (64-128GB) memory cards!

    And also implement a robust secure tightly integrated OS level RDP functionality that worked reliably everytime (esp if they could add the ability to securely remotely boot a computer),

    THEN I would have NO NEED for complete Windows functionality, nor would I risk the same degree of data exposure as carrying about a laptop!

    In other words, a truly converged device with both phone, user exchangeable memory, and remote secure policy driven robust reliable RDP would produce a compelling device offering me all the functionality I need.



  • 0 Hide
    halcyon , February 7, 2013 10:31 AM
    masSo is the goal to simply reproduce a laptop in the form factor of a tablet?

    For many, yes, as they've told themselves that that is more portable (I don't see it but to each their own).