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Video playback
Video decoding performance was tested using the Iron Man 2 trailer in multiple formats. Windows Media Player was used for the H.264 QuickTime clips, while Firefox hosted the windowed YouTube test. We tested a bit differently this time. Windows 7's Performance Monitor was still used to log CPU utilization for the duration of the trailer, but we played each video three times and grabbed the lowest numbers for each. This method should provide representative numbers largely untarnished by CPU utilization from background processes.

We ran our video tests first using the high-performance battery profile...

  CPU utilization Result
Iron Man 2 H.264 480p 0-6.8% Perfect
Iron Man 2 H.264 720p 0-5.2% Perfect
Iron Man 2 H.264 1080p 0-5.2% Perfect
Iron Man 2 YouTube 720p windowed
(Flash 11)
1.3-13.4% Perfect

...then a second time with the Battery Saving profile.

  CPU utilization Result
Iron Man 2 H.264 480p 0-13.4% Perfect
Iron Man 2 H.264 720p 0-9.9% Perfect
Iron Man 2 H.264 1080p 0-16.5% Perfect
Iron Man 2 YouTube 720p windowed
(Flash 11)
10.7-26.7% Smooth, some dropped frames

HD YouTube video isn't as smooth in the Battery Saving mode, but otherwise, video performance on the Zenbook is excellent.

Battery life
To gauge run times, we conditioned our systems' batteries by cycling them two times. For the web browsing test, we used TR Browserbench 1.0, which consists of a static version of the TR home page that cycles through different text content, Flash ads, and images, all the while refreshing every 45 seconds. Then, we tested video playback in Windows Media Player by looping an episode of CSI: New York encoded with H.264 at 480p resolution (straight from an HTPC). Wi-Fi and Bluetooth were enabled for the web browsing test and disabled for movie playback.

We attempted to keep the display brightness consistent across all systems, choosing levels corresponding to a readable brightness in indoor lighting. A 40% brightness setting was used on the Acer 1810TZ, Asus A53T, Asus K53E, Asus N82Jv, Eee PC 1015PN (in its "Super Performance" mode), HP Pavilion dm1z, Toshiba Satellite T235D. We used a 50% setting on the Aspire One 522, Eee PC 1015PN in "Battery Saving" mode (since disabling the Nvidia GPU seemed to reduce brightness), as well as on the U33Jc. Because of their dim, matte displays, the HP ProBook 6460b and AMD A8-3500M systems were tested at 70% brightness settings. Conversely, because of their high display luminosities, the Zenbook UX31 was tested at a 25% brightness level and the Series 9 was tested at 30% (and with its adaptive brightness setting disabled).

Wow. Over six hours of web-browsing run time on a notebook this thin, light, and powerful is quite a feat, to say the least. Even more impressive is the fact that switching to the uncompromising high-performance profile doesn't put much of a dent in run times.

Surface temperatures
We measured temperatures using an infrared thermometer at a distance of 1" from the system after it had been running TR Browserbench 1.0 for about an hour.

28°C
83°F
 
35°C
96°F
 
30°C
86°F
 
28°C
83°F
 
30°C
86°F
35°C
94°F
 
31°C
87°F
 
31°C
88°F
 
30°C
86°F
 
28°C
83°F

No surprises here. To get such long battery run times in such a tight chassis, the Zenbook UX31 needs power-efficient hardware—and power-efficient hardware doesn't dissipate a ton of heat. Besides, the aluminum enclosure helps dissipate that heat better than, say, plastic. That's probably why the Zenbook is whisper-quiet in most situations. Even when the cooling fan goes off, the noise produced is more of a breathy whooshing sound than a whine or hum.