Apple's 11-inch Upgraded MacBook Air: Do 1.6GHz and 4GB Make a Difference?by Anand Lal Shimpi on November 6, 2010 2:35 AM EST
Intel ships microprocessors, even those running at the same frequency, at varying voltages. Chips with lower leakage ship at lower voltages, while higher leakage chips ship at higher voltages. All CPUs have to ultimately fit within the same power envelope, but anything below that max TDP is fair game.
Running at a higher frequency generally requires a higher voltage, which in turn increases power consumption. I ran the upgraded 11-inch through all of our battery life tests to measure its impact.
Light Web Browsing
Here we're simply listing to MP3s in iTunes on repeat while browsing through a series of webpages with no flash on them. Each page forwards on to the next in the series after 20 seconds.
The display is kept at 50% brightness, all screen savers are disabled, but the hard drive/SSD is allowed to go to sleep if there's no disk activity. The wireless connection is enabled and connected to a local access point less than 20 feet away. This test represents the longest battery life you can achieve on the platform while doing minimal work. The results here are comparable to what you'd see typing a document in TextEdit or reading documents.
Flash Web Browsing
The test here has three Safari windows open, each browsing a set of web pages with between 1 - 4 animated flash ads per page, at the same time. Each page forwards onto the next after about 20 seconds.
As always, the display is set to 50% brightness, audio at two bars, screensaver disabled and the hard drive/SSD is allowed to go to sleep if idle. The wireless connection is enabled and connected to a local access point less than 20 feet away.
Multitasking Battery Life
Our final battery life test is the worst case scenario. In this test we have three open Safari windows, each browsing a set of web pages with between 1 - 4 flash ads per page, at the same time. We're also playing an XviD video in a window all while downloading files from a server at 500KB/s.
Overall the upgraded hardware resulted in a minimal impact to battery life. The worst impact was in the Flash web browsing test in which the upgraded system delivered 93% of the battery life of the base 11-inch MBA. The remaining two tests offered between 94 - 95%.
Given the 15% average improvement in performance when you need it, a 6% average reduction in battery life isn’t bad.