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
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  • JarredWalton - Tuesday, September 22, 2009 - link

    What I would love is to have a definitive Linux source that I can use that will "just work". But that's probably asking too much. I've now got suggestions to try the Ubuntu Netbook Remix, Moblin on the NV58, and Archlinux.

    And hey, if anyone lives near Olympia, WA and wants to come give the Linux install some fine luvin' let me know. LOL
    Reply
  • stmok - Wednesday, September 23, 2009 - link

    quote('What I would love is to have a definitive Linux source that I can use that will "just work".')

    That isn't going to happen. Simply because Linux isn't Windows or OSX. They approach things with different paradigms.

    Reply
  • Per Hansson - Tuesday, September 22, 2009 - link

    Hi, something I have noted when installing AMD laptops with a clean RTM WinXP disc and not the bundled one that includes all drivers + lotsa more crap you don't want;

    In all cases the systems have not been throttling the CPU speed or CPU voltage, I have had to install the AMD PowerNow! driver and then everything has worked (even though both AMD and Microsoft say this is included with XP!)

    The difficult part is actually finding the driver, since both AMD and MS feels it is not needed it can be a real pita, please verify with CPU-Z or similar if your systems have this issue
    Reply
  • JarredWalton - Tuesday, September 22, 2009 - link

    Vista definitely worked properly - I saw CPU speeds of down to 1050MHz (5.25 x 200) on the NV52. Since XP and Win7 both achieve similar results, I think it's working right but would have to check. I'll try to be more careful for the next tests. :) Reply
  • jasperjones - Tuesday, September 22, 2009 - link

    I assume you ran Ubuntu with the 32-bit Flash plugin (that's available on x86-64 via nspluginwrapper (Netscape plugin wrapper).

    I'd be curious to see how results are with the native x86-64 Flash which is available as an alpha on Adobe Labs.

    For the last two or three years, I've had nothing but problems with 32-bit Flash on a 64-bit OS and those problems finally somewhat subsided after moving to the 64-bit native alpha build.
    Reply
  • clavko - Tuesday, September 22, 2009 - link

    Actually, graphics card power management with open source ati drivers (xf86-video-radeon and xf86-video-radeonhd alike) is not up to par with custom power management of fglrx proprietary driver. If tests were made using open source drivers, some of the battery time difference should account for that.

    However, I find it quite fair comparing Windows to Ubuntu, given that Ubuntu really is considered vanilla, desktop user distro. Obviously, things are not exactly "there" yet, but I'd be interested in power consumption with newer fglrx drivers, perhaps on OpenSUSE.
    Reply
  • strikeback03 - Tuesday, September 22, 2009 - link

    On my laptop (T40, 1.86GHz Pentium M Sonoma) I primarily use Ubuntu, with XP when I need Photoshop or Lightroom. I never measured the battery life exactly, but never felt it was that different, certainly not by a third. Do you have the scripts to run the internet test I could try and see what my results are?

    I also never felt Firefox was notably different between XP and Ubuntu, both misbehave in different ways. The notable exception is flash in 64bit Ubuntu on my desktop, which is of course more hit-or-miss.
    Reply
  • JarredWalton - Tuesday, September 22, 2009 - link

    Send me an email. Reply
  • gwolfman - Tuesday, September 22, 2009 - link

    When I originally purchased my Dell Mini 9, it shipped with Ubuntu. Rather than coming with the standard/original kernel, it came with the Low Power Intel Architecture (LPIA) kernel. I'm not sure what optimizations are done with regards to the kernel, but do you think it's worth looking into with regards to the bad numbers you got from the default kernel bundled with your Ubuntu install? Maybe there are some optimizations for battery life in there that are not included in the standard kernel. Reply
  • vol7ron - Tuesday, September 22, 2009 - link

    As nice as these tests are, I think the reliability/consistency may be overlooked a little bit. I'm not saying it's not reliable/consistent enough, you've already touched on that in the final paragraph, with regards to the websites themselves. What I'm saying is that there are other factors that may be affecting battery life.

    Are you using a multimeter to measure the power consumption, or are you just letting the battery drain and measuring time? I'm guessing that if you just let your computer start up and run it's battery drain naturally (no erroneous applications running), the battery life would also vary in minutes.

    I also am assuming that these devices aren't cooled to the same temperature, before tests begin. Heat not only dissipates the energy stored in the battery, but it also requires more power to the fans for cooling. As I've touched on in another article, processor speeds vary - that's something that is truly hard to keep consistent, since it is irrelevant to BIOS settings. It'd be interesting to see if a processor running at 2.096 vs one running at 2.104 over an extended period of time has enough impact on battery life.

    That being said, it's also known that processors vary in clock speed even after it's started, so I'm not sure if any points I've made can be applied in setting a realistic control at this point.

    My last point is about the battery itself. Manufacturers claim the battery is "good for" a certain period of time, but these batteries are often "cheap" in quality. I think a few uses could impact the natural battery life; this goes back into testing regular start-up/shut-downs, w/o running any tests.
    Reply

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