The Three Power Profiles

There are three power profiles ASUS and NVIDIA have defined on the Prime: Normal, Balanced and Power Saver. Normal allows the CPU to run at up to 1.4GHz with only a single core active, and 1.3GHz otherwise. Balanced is the default setting and it drops maximum CPU clock to 1.2GHz and favors lower clock/voltage targets on the curve compared to Normal mode. Power Saver caps CPU frequency at 1GHz with 1 - 2 cores active, 760MHz with 3 cores active and 620MHz with 4 cores active. It's unclear what the impact is on GPU clocks/performance.

Regardless of power profile, video playback capabilities are untouched - all profiles are able to play 1080p High Profile H.264 content at up to 40Mbps.

The performance impact of these various profiles varies depending on what you're doing. I ran a mixture of CPU and GPU bound tests in all profiles to measure their impact. The results are below:

I reformatted the SunSpider and BrowserMark scores to keep the magnitude of the numbers in line with the rest in the chart, and to make higher numbers = better performance across the board. For the most part you can see that the difference between Normal and Balanced is pretty small. Numerically it works out to be a 5 - 15% gap depending on the benchmark. The latter end of the range is big enough where the performance conscious will want to stay in Normal mode, but it's possible to do without it.

It's interesting to note that the impact on GPU performance isn't that major across the board. It looks like NVIDIA is primarily modulating CPU speed here. The impact on JavaScript rendering performance is huge when you enable the Power Saving mode. In this state the Prime performs like a Tegra 2 based Gingerbread phone.

Power Profiles & Super IPS+ Toggles

Unlike (far too) many of its competitors, ASUS limits its customizations to those that are almost purely functional. ASUS is clearly aware of the fine line between useful improvements and clutter.

The most obvious customization is in the Quick Settings tool:

ASUS' implementation is far busier but it's all extremely useful. You get one tap access to Super IPS+ mode, as well as one tap switching between Power Saving, Balanced and Normal power profiles. I'm pleased to report that toggling any of these modes is pretty much instant, there's hardly any lag between when you tap a button and its impact takes effect. Response time is a particularly important as it directly impacts how frequently the tool is used. In this case I have no issues switching between power profiles because it's pretty much effortless.

Video Playback: Blu-ray Quality in a Tablet Camera Quality
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  • Penti - Thursday, December 1, 2011 - link

    It looks like they have finally a pretty good product and software, they should dump the Eee pad and the redundant awkward name now and it would be even better :)

    Would love to see better optimized software, but this is what you could have expected plus with a great screen and I wonder how well it would work as a thin-client with Citrix? Keyboard and touchpad should make it a pretty good experience, does it? Chromebooks can just forget it any way :) Here we have form factor, local software, multimedia (Chromebooks are not even having accelerated H.264 as standard) and so on. With keyboard docked and standard, and not just a browser that was obvious would be replaced by a Android distribution of some kind any way. Maybe that time is now. Even though I wouldn't except Asus to complete that process. Fun to see them kinda getting there act together though.
  • Malih - Thursday, December 1, 2011 - link

    I agree that Eee is an awful name, especially for a flagship/cutting-edge product.
    Eee is associated with low-end Atom netbooks, since that's the first device that uses the name. And I always hate that Samsung name their mobile devices Galaxy.

    IMHO, the name Zenbook sounds good, maybe they should invent something consistent with that for their top-line tablet, Zenpad?
  • Penti - Friday, December 2, 2011 - link

    Zenbook is still kinda awkward but it's better, ZenPad doesn't do anything for me and sounds silly. Transformer Prime is a pretty good name. Transformer might cause some confusion though, if they decide to release one without any keyboard attachment. Their Windows tablet PCs (slates as of now) might as well get some updated finish and release as a Zenbook slate though.
  • MamiyaOtaru - Thursday, December 1, 2011 - link

    "The 16:9 panel measures 10.1-inches diagonally, giving it a larger surface area than the iPad 2's 9.7-inch 4:3 display. "

    If you do your math, this isn't actually true. A 10.1" 16:9 display has a surface area of 43.58", while a 9.7" 4:3 display has a surface area of 45.17". This is one of the main reasons behind widescreen, they get to trumpet a larger diagonal measurement while actually saving costs on smaller total area. I am a little disappointed you fell for it.
  • MamiyaOtaru - Thursday, December 1, 2011 - link

    some numbers you can plug in for verification (rounding all around!):
    16:9 10.0" display has sides of 8.8 and 4.951. 8.8/4.95 ~= 16/9 (correct ratios). 8.8² + 4.95² ~= 10.1² (correct dimensions for given diagonal, shown via pythagorean theorem).
    area then: 8.8*4.95 = 43.96.

    4:3 9.7" display has sides of 7.76 and 5.82. 7.76/5.82 ~= 4/3 (correct ratios). 7.76²+5.81² ~= 9.7² (correct dimensions for given diagonal, shown via pythagorean theorem).
    area: 7.76*5.81=45.09.

    45.09 is larger than 43.96. Ipad2 has a screen with a larger surface area. Run the numbers. Do it without dropping as many places as I did in this post, result will be the same. Again, disappointing

    (I don't have a horse in this race, I own no Apple products. I do hate widescreen monitors though)
  • MamiyaOtaru - Thursday, December 1, 2011 - link

    interestingly, the gap was closed somewhat when I dropped more places in typing up the second post. The first is more accurate, and the gap is bigger. But they both show the ipad as having more surface area, and that will hold true with pretty much whatever level of exactitude one wishes to calculate it
  • Anand Lal Shimpi - Thursday, December 1, 2011 - link

    It's actually a 16:10 panel, my statement was incorrect. But the Prime's display measures roughly 8.5" x 5.25". The iPad 2 by comparison measures approximately 7.75" x 5.75". 44.625 in^2 vs. 44.5625 in^2, giving the Prime a slightly larger display (albeit negligible).
  • Solandri - Thursday, December 1, 2011 - link

    At 9.7" diagonal and 4:3 aspect ratio, the iPad 2's screen is 7.76" x 5.82".

    At a 10.1" diagonal and 16:10 aspect ratio, the Prime's display is 8.56" x 5.35".
  • Solandri - Thursday, December 1, 2011 - link

    Anand's math is right. His aspect ratio is wrong. The Transformer Prime has a 1280x800 screen, which is 16:10, not 16:9. At a 16:10 aspect ratio, you end up with 45.85 square inches of surface area.

    Personally I think 16:10 is the "right" aspect ratio for a multifunction device. You waste10% of the screen when displaying a 16:9 video. A 4:3 device wastes 25% of the screen. The extra width is nicer for web browsing too.

    Where the 4:3 screen does better is displaying pages scanned from paper or magazines. Subtracting a 1-inch margin along all four sides, a 4:3 screen wastes 4% of its screen displaying a Letter-sized sheet of paper, while a 16:10 wastes 13%. (With A4 paper and 2-cm margins, it's reversed. The 4:3 wastes 12%, the 16:10 screen wastes 6%.)

    But that's counter to the whole point of tablets - to free us from the shackles of a paper-bound world. As a media consumption device, I think 16:10 is the better aspect ratio. It's almost exactly the golden ratio too (1.62), so most art which is produced will fit in it better.
  • GnillGnoll - Friday, December 2, 2011 - link

    For browsing the web and reading, portrait orientation is often a better fit. Though it requires a certain minimum width and resolution to work really well.

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