One of the Nano's biggest selling points is its incredibly low idle power consumption, a fact that is born out by our tests that clearly show, the entire Nano platform uses a couple of Watts less than the Atom platform. Obviously there are a lot of other factors involved in power consumption besides just the chips themselves but it would seem that at idle, Nano is just a nose ahead.
However, when we look at power consumption when under load we see a very different story. Taking an average reading while running PCMark Vantage, Nano's power consumption rockets up by over 14 Watts. The Atom platform, on the other hand only increases by just over 5 Watts, which is a very impressive feat.
It's a similar story when looking at video playback. For the less taxing codecs, Nano's power consumption stays within spitting distance of Atom but moving to the 480p and 720p h.264 footage and the Nano's power consumption rockets up. Certainly it would seem if you plan to use your netbook as a portable video player, choosing an Atom platform will give you longer battery life.
Now normally we'd leave things there and draw our conclusions based on those results but because power consumption is such an important factor for these processors we wanted to do some further testing. So we decided to look at total power draw for a given task, e.g. if I want to turn my laptop on, edit a photo, upload it to a website, and turn the laptop off again, which CPU will do this using the least total power. So, to test this we devised an extra power consumption test.
We started by plugging the test systems into a Watts Up! mains power consumption meter, which can record total power used over a period of time. We then ran PCMark Vantage (we disabled the HDD test) and recorded how much power was consumed and how long it took to complete this test.
The results make for interesting reading because it would seem for all the differences in performance and power consumption the two platforms actually get the majority of tasks done in the same amount of time and while consuming about the same amount of electricity.
To confirm this we quickly fired up the Photoshop portion of our real world test suite and checked the power consumption used in one run through. Although Atom took a couple of minutes longer to complete the task, both systems used nearly identical amounts of power. Ultimately, this one's too close to call and will depend largely on your usage.