Battery Life - Technically, No Better

Now it's time to talk about battery life. Let me run down the tests real quick. This is a combination of the tests Jarred runs in our standard notebook/netbook reviews and the tests I run in my Mac reviews. WiFi was always enabled and connected to an access point 20 feet away. The screen brightness was set to 100 nits and Windows 7 was configured to use its Power Saver battery profile.

The idle test is exactly what you think it is. The notebook just sits at the Windows 7 desktop with no screensaver active until it runs out of battery power. This is a good indication of the best battery life you'll get out of the notebook (e.g. just typing in a text document).

The light web browsing test comes from our Mac reviews and cycles through a series of web pages, pausing on each one for 20 seconds before going on to the next one. There are no flash ads on the web pages. This is the lightest load you'd see when browsing the web. A playlist of MP3s loops in the background.

The average web browsing test also comes from our Mac reviews and cycles through a series of web pages, pausing on each one for 20 seconds before going on to the next one. Each page has between 1 and 4 flash ads on it and there are three concurrent IE8 windows open, each doing the same thing. A playlist of MP3s loops in the background.

The heavy web browsing test opens four tabs in IE8, each heavily loaded with flash ads. The tabs stay open for a short period of time before the cache is cleared and the browser is closed. The system sits at the desktop for a short duration before launching IE8 once more and opening the same four tabs. The test repeats until the battery is drained. This should be close to the worst case battery life while browsing the web.

Our video playback test loops a 720p x264 movie in Media Player Classic Home Cinema x64 until the battery dies. The player uses any GPU acceleration present in the system.

Finally, the heavy downloading/multitasking test mixes a bunch of these tests together. The average web browsing test runs while a 480p XviD movie plays and while a download script executes and downloads files at a constant 500KB/s from a server.

I kept as many variables constant as possible between the two systems. Both are configured with the same amount of memory, with the same HDD and are set to the same brightness. Both systems are normalized to the same battery capacity to produce an apples-to-apples comparison of battery life.

And now, the results:

Battery Test Core 2 Duo P8700 (2.53GHz) Core i5-540M (2.53GHz) Arrandale Advantage
Idle 216 minutes 215 minutes None
Light Web Browsing 177 minutes 188 minutes +6%
Average Web Browsing 177 minutes 186 minutes +5%
Heavy Web Browsing 174 minutes 176 minutes None
Video Playback (x264) 132 minutes 134 minutes None
Heavy Downloading/Multitasking 144 minutes 147 minutes None

 

For the most part there's actually no improvement in battery life due to Arrandale. There are a couple of instances where we see a 5 or 6% increase in staying power but these two platforms are basically equal. That's great when you consider how much faster Arrandale is than its predecessor, but it's not great when you remember that we're talking about a fully power gated 32nm processor here.

If we look at our desktop Clarkdale results we see that idle power for Intel's 32nm part isn't very good. It's actually worse than the 45nm Lynnfield platform from earlier this year. Intel confirmed that there is a lot of optimization that has to happen with Arrandale. It looks like there are some silicon level tweaks that are on the roadmap to be implemented but we won't see them until the middle of 2010. That means while the first Arrandale notebooks won't offer any more battery life than their predecessors, the second wave of Arrandale should fix that.

There's also one more thing to worry about. All of our battery life tests are carefully constructed to make sure they execute the same amount of work on all systems. Twenty seconds takes the same amount of time regardless of how fast your CPU is. As we've already seen, Arrandale is nearly 20% faster than the current mobile Core 2 Duo at the same clock speed. It is possible for you to get much worse battery life out of Arrandale simply by doing a lot more work. Intel estimates that if we were to loop Cinebench over and over again we'd see about 30% worse battery life on Arrandale vs. the previous generation mobile Core 2. The reason being that Arrandale would be much faster, but draw more power. It would be doing more work over the course of the test.

For an end user all this means is that you can do things like encode videos faster on Arrandale than you could before. You can either do the same amount of encoding, faster, without hurting battery life, or you can do more encoding, in the same amount of time, while reducing battery life. Just something to be aware of as Arrandale notebooks have the ability to be just as power efficient as existing notebooks, but can easily be more power hungry if you let them.

Performance - A Huge Improvement Final Words
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  • silverblue - Friday, January 08, 2010 - link

    Hmm. Reply
  • silverblue - Friday, January 08, 2010 - link

    Nope, it's just me (damned similar names)... however, the Clarkdale article has vanished from the front page. :| Reply
  • dnenciu - Thursday, January 07, 2010 - link

    I don't know why are reviewers so happy about Arrandale.

    You basically get 20% improvement compared to the same "clockspeed" c2d.

    What about the fact that Arrandale only goes 2.53Ghz and 2.66 for the extreme edition.

    C2D already goes to 3.33Ghz

    Yes turbo boost increases the 2.53Ghz to 3.06 but that is only if one core is used and the laptop has proper cooling.

    The c2d at 3.06 Ghz can run two cores at that speed.

    So what we are seeing is last years performance and same battery life.

    And also last years integrated GPU. That now you don't even have a choice to replace with a 9400m.

    I really feel underwhelmed by this chip release.

    Lets hope that they can improve it in the next release because for me this one is a big flop. :(
    Reply
  • iwodo - Monday, January 04, 2010 - link

    I record CoreiX series was proved to be much more efficient then C2D in some previous Anand article. Now we are actually getting different results. So Westmere gets more performance by using more energy and transistors.

    And this isn't an fair comparison either, C2D platform uses an 65nm of IGP and 45nm of CPU. While Westmere gets one process node improvement in both.

    So in terms of pure Power / Peformance, it looks like C2D still has an edge. I would love Intel make an 32nm of C2D. ( Which would play well with ION2 and Apple would love it. )

    I hope SandyBridge would come soon as an True successor to C2D. Nahamlem to me is just an CPU made for Server.

    Side Notes - Intel GPU, although performance is fast enough in lowest settings, still gives worst Image Quality compare to other IGP. Which gains an unfair advantage. I hope some Internet review will point this out.
    Reply
  • JarredWalton - Monday, January 04, 2010 - link

    On the desktop, Core i7 (and particularly Lynnfield) provided great idle power results. My testing of Core i7 notebooks on the other hand shows that the quad-core variant is a power guzzler. Reply
  • zicoz - Monday, January 04, 2010 - link

    How does this compare to the Clarkdale on the HTPC front? Does it support LPCM and bitstreaming? I have this dream of building a HTPC from laptop parts, and if this supports the same stuff as the Clarkdale then this could be it. Reply
  • jasperjones - Monday, January 04, 2010 - link

    Anand writes:

    "The first mainstream Arrandale CPUs are 35W TDP, compared to the 25W TDP of most thin and light notebooks based on mobile Core 2. Granted the 35W includes the graphics, but it's not always going to be lower total power consumption."

    --

    From the benches shown here I infer: the 540M is substantially faster than the fastest available C2D. Which is to say, the T9900 (unless I forget some Core 2 Extreme model) whose TDP is 35W. There is no P-series C2D that provides the performance of the 540M. Thus, an apples-to-apples comparison is really vs. a T9900 (or Core 2 Extreme) which has 35W TDP and *no* integrated graphics.

    And even if you aren't d'accord with my statement above: logically, you can't just compare the P8xxx/P9xxx models' TDP of 25W with Clarksfield's TDP of 35W. After all, Clarksfield includes essentially all Northbridge functionality. The Northbridge for Penryn is rated 12W TDP. So, really, 35W < 25W + 12W = 37W (or, 35W < 35W + 12W = 47W).
    Reply
  • jasperjones - Monday, January 04, 2010 - link

    ^^^ of course, I mean Arrandale, not Clarksfield. Reply
  • JarredWalton - Monday, January 04, 2010 - link

    Even then, TDP ratings aren't actual power requirements. They're more like a limit on the thermal output, so you need 35W of cooling on a 35W CPU, even though at idle it probably uses only 5W.

    As far as performance, Arrandale in most cases is about 20% faster. The T9900 is 3.06GHz compared to 2.53GHz on the P8700, which is a 20% performance boost. That would make the T9900 about equal to a 540M. At that level of performance, I would expect the battery life advantage to be more like 5-10% for Arrandale. (Despite the 35W vs. 25W TDP, my experience is that for typical battery life testing scenarios, the 35W TDP CPUs are not substantially worse than 25W CPUs.)
    Reply
  • Wolfpup - Monday, January 04, 2010 - link

    I'm still surprised that we don't get 32nm quads yet, though I suppose from Intel's perspective it makes sense-probably make the most from their mid range "high end dual cores".

    I'm glad to see there are some new chipsets with this too. PM55 has USB problems, that OEMs don't seem to be addressing super well. There's some talk that the newest drivers from Intel combined with a hotfix from Microsoft that isn't even for this chipset fixes it, but not 100% sure if it really does.
    Reply

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