Test Setup

As stated, we are testing four different operating systems. In order to keep the number of benchmarks manageable, we are focusing on two primary battery life scenarios. Our first test is an Internet web-browsing scenario. We configure the chosen browser to load three websites that contain Flash content every 60 seconds. When the battery level goes critical (usually 1%, although Windows 7 doesn't let us set this lower than 3%) the system shuts down. The second test is DVD playback battery life, again with the system set to run until the battery level is critical. The various operating systems don't necessarily give you the same level of control over power saving features, so we tested a couple scenarios on each Windows OS.

Windows XP

Windows XP gives you the least control over power saving features. We test two scenarios, one using the Portable/Laptop profile and the other using the Max Battery profile. We don't have specific details on what these settings mean in terms of maximum CPU performance, but it's clear that they do affect performance. They also impact battery life, and most people only want enough performance when running on battery life for their system to work properly. We did not experience any difficulties watching DVDs or surfing the Internet, although more CPU intensive tasks may have problems when using the Max Battery profile. On the Portable profile, the HDD is set to power down after five minutes, while the Max Battery profile has it set to power down after three minutes. We also measure LCD brightness with a colorimeter and set it as close to 100 nits as possible.

Windows Vista/7

Similar to Windows XP, we test two different power profiles in Windows Vista and 7: Balanced and Power Saver. These profiles correspond roughly to the same settings as the Windows XP profiles, but this time we have more control over the various details. For Windows Vista and 7, we use the following settings under Balanced.

The hard drive is set to power off after five minutes. The wireless adapter is set to medium power saving, hybrid sleep is enabled, and USB selective suspend is enabled. PCI-E link state power management is set to maximum power saving. The minimum processor state is set to 5% and the maximum processor state is 100%; we don't know how this specifically affects CPU clock speeds, and if you want to run a similar test make sure your notebook manufacturer doesn't specify different values. Search and indexing is set to power saver and adaptive display is disabled. Again, we calibrate the LCD to run at 100 nits, which is 35% brightness for these two laptops (three steps above minimum brightness).

The Power Saver profile uses the same settings in most areas, but we set the hard drive to power down after three minutes, the wireless adapter is at maximum power saving, and the maximum processor state is 50%. Windows 7 does include a few other areas that you can tweak, but most of these relate to LCD dimming in order to conserve power. This is not to say that Vista and Windows 7 are the same, because as we will see in the results there are some definite differences.

Ubuntu 9.0.4 (Jaunty)

There aren't a lot of power saving features available for tweaking within Linux - at least not that I could find. We configured the LCD to never shut off (just like on Windows), and set the system to shut down at 3% battery - the minimum we could specify. We also disabled LCD dimming. Honestly, I don't know nearly as much about Linux as Windows, but I did my best to get Linux installed properly on the two notebooks. As anyone who has used Linux before can tell you, getting driver support is sometimes a real pain in the rear.

Generally speaking, both systems also felt far more sluggish running Linux, especially for typical web browsing. We used Firefox 3.0 initially and then updated to 3.5 - not as easy as I would like under Ubuntu, and I have no idea why the latest build is called Shiretoko in some places and Firefox 3.5 in others. Whatever. Both versions of Firefox felt incredibly slow, but that was with Flash enabled. With the FlashBlock add-on, Internet performance was significantly better, but that isn't a fair comparison to the Windows browser tests. As a point of reference, we ran the same test under Windows Vista and achieved significantly better battery life. We will get to those results in a moment.

Our issues with configuring Ubuntu don't end with the browser, however. On the Intel-based NV58, we could not get LCD brightness to function properly. The result is that the LCD ran at maximum brightness during our tests, which obviously results in lower battery life. We tried to find an updated driver for the Intel GMA 4500MHD graphics, but so far we have been unsuccessful in addressing this issue. The AMD-based NV52 wasn't any better, but for different reasons. We could find updated drivers from ATI, but after repeated attempts we never did get them to function properly. We were left with running the proprietary fglxr 8.600 driver, and while it worked fine in general we had problems with DVD playback. VLC repeatedly crashed during our benchmarks, sometimes after a few minutes, sometimes after 50 minutes. Eventually, we decided to uninstall the proprietary ATI driver and test out the open-source MESA driver. Surprisingly, the open-source driver actually provided a better experience, although we aren't looking at 3D performance where ATI's fglxr driver likely has an advantage.

The short story is that while everything eventually worked out okay on the NV52, the number of headaches we encountered trying to get everything working properly under Ubuntu is more than a little frustrating. You get a sense of accomplishment once everything is working, or at least I did, but that's not something most people are interested in doing. Most people view computers as a tool and they wanted to "just work"; they don't want to scour the Internet looking for instructions on how to manually install the latest drivers/application/whatever. If you're Interested in a more detailed look at Linux, we suggest you read our Ubuntu 8.04 Article. The only area of Linux that we're testing today is battery life.

Index Gateway NV52 (AMD) - Battery Life


View All Comments

  • JarredWalton - Tuesday, September 22, 2009 - link

    I don't think it works quite like that. If you set it to 0%, I believe that's the minimum CPU speed (i.e. 5.25 x 200MHz on the NV52 and 6 x 200MHz on the NV58), while the higher percentage may try to target a maximum speed. 100% would be the normal CPU speed, but would 50% be half-way between minimum and maximum?

    I'd have to investigate more, but I do remember testing with CPU-Z and seeing CPU clocks go well above the 50% mark. I think at best it's approximate, as you suggest, and how accurate it is likely varies greatly with the CPU - and even BIOS options.
  • trochevs - Tuesday, September 22, 2009 - link

    Looking the starting times (startup and resume) I have the feeling that Ubuntu has some kind of problem on your hardware. I have quite bit experience with Dell and Lenovo and Ubuntu 9.04 is always faster to boot compare to any Windows. It is not only my experience, but I am doing test on one senior citizen and one teenager. They both agree with my observation. You should press Alt-F1 during the boot and check for any errors. Gateways could have some additional peace of hardware that does not work correctly under Ubuntu and the kernel has to wait to time-out.
    In regards out of the box experience you should get hold of the system that is optimized for Linux (Ubuntu) just like the Gateway is optimized for Windows. www.system76.com or Dell http://www.dell.com/content/topics/segtopic.aspx/u...">http://www.dell.com/content/topics/segt...s=19&... would be good start. Then you don't have to fool with drivers. I would love to see how much optimization has been done by System76 and Dell.
  • ekul - Tuesday, September 22, 2009 - link

    It's true; ubuntu 9.04 boots very quickly and 9.10 will be even better. On my netbook and my desktop 9.04 boots in a lot less then 30 seconds. I agree something isn't quite right with the boot procedure.

    The other thing to keep in mind for linux boot times is once the desktop is displayed the system is fully up. No background loading, no delayed startups. On Vista and 7 I find after the desktop appears it will take another 30-45 seconds before the HD is done reading and the system is responsive
  • oyabun - Tuesday, September 22, 2009 - link

    Thank you very much for an enlightening article. I am one of the people who indeed care for battery life!

    Regarding your testing methodology where you drain each battery over and over again, wouldn't it be more efficient to take the battery out of the equation (and physically remove it) completely? Just measure the Wh consumed by the power brick during 30 or 60 minute runs and extrapolate to the capacity of the battery. That would greatly reduce your testing times.

    You should of course measure at the DC end of the transformer, otherwise you should factor in it's efficiency.

    You could even calibrate the whole procedure with a single battery powered run. It certainly beats what you are currently subjecting yourself to! :-)

    Keep up the good work!
  • JarredWalton - Tuesday, September 22, 2009 - link

    My experience is that laptops typically switch to different power states on AC vs. DC power, even if you have all the settings the same. It's possible to estimate battery life, but I do like to do "real world" testing where possible. Anyway, it's not a bad idea and I may do a follow up article at some point looking at just the power numbers. Taking the power transformer efficiency out of the equation isn't something I'm equipped to do right now, unfortunately. I can measure power at the outlet... and that's it. And it's only accurate to ~1W there so I'd need a better device than my current Kill-A-Watt.

    BTW, have you ever stared at a small Kill-A-Watt display while running tests? Frankly, running battery tests where I can walk away and collect the results later is less painful all around! :)
  • oyabun - Wednesday, September 23, 2009 - link

    Of course a Kill-A-Watt won't cut it! You need a datalogger on a separate PC and a power gauge, logging the total energy consumption over any period of time unattended. With such a setup you would be able to measure from the DC side by splicing the wires leading from the transformer to the notebook. And, naturally, a datalogger support more than one gauge, so you could measure in parallel.

    I understand what you mean when you say that power profiles behave differently under AC. It is possible though your (and mine) experience is based on Windows XP. Perhaps Windows 7 are more consistent.
  • oyabun - Wednesday, September 23, 2009 - link

    I didn't see the comments by Kibbles before. Our posts convey the smae message!
    And I concur, the power supply testing team appears to have the tools for the job.
  • strikeback03 - Wednesday, September 23, 2009 - link

    Yeah, IIRC they're also in Europe, while Jarred is in Seattle or somewhere out west. Reply
  • JarredWalton - Wednesday, September 23, 2009 - link

    There's more to it than that, but suffice it to say I don't have power testing equipment and it's not high on my list of priorities right now. Rough estimates are sufficient on the power side of the equation, since you get whatever power brick the laptop comes with. It's not like you can upgrade to a more efficient power brick with a Dell laptop. Reply
  • Kibbles - Tuesday, September 22, 2009 - link

    "maybe borrow it from the powersupply setting team"

    I meant "powersupply testing team".

    Also for the convenience of being able to walk away. As long as you get a voltmeter with logging capability, you can leave it to do it's thing and just pull up the logs.

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