One of the eye-catching things about the MacBook Air announcement was the availability of a solid-state drive (SSD) as a standard option, replacing the mechanical hard drive. For a not-insignificant $999, you can upgrade the regular hard drive to 64GB of pure memory chips. SSDs have been around for years, but they’re just now starting to become affordable in consumer-oriented computers.
Apple says the SSD offers higher performance and greater durability. They do not make any claims about battery life, but it’s been widely rumored that the solid-state approach saves power – after all, there’s the “no moving parts” business. But review site Tom’s Hardware says that’s not the case: in fact, they claim that switching to a SSD reduces your battery life.In an article peppered with graphs and benchmark tests, the Tom’s Hardware writers conclude that although the peak power consumption of hard drives is higher than that of SSDs, that peak is not often reached in real operation, since drive heads to not tend to be moved long distances. By contrast, they claim, SSDs draw a relatively steady amount of power the whole time they’re in operation. Their end result is that for the drives they tested, switching to SSD could cost anywhere from 5% to 30% of your runtime.
The results have not gone unchallenged – in fact, commenters on the article have taken serious issue with the methodology employed, focusing on the question of whether the SSD-equipped computer might actually have done more work in the same amount of time. The results are also out of line with some other tests – for example, an early MacBook Air review from AnandTech found an 11 to 17% improvement in runtime with the SSD.
What’s the bottom line here? It appears to be that, like most benchmarks, battery life benchmarks are only an approximate representation of real-world performance. In my opinion, the effect on battery life one way or the other is not significant enough to justify buying or rejecting the SSD. You need to look at the other potential benefits here – do you really need to speed up a box that has basically lackluster specs as a performance powerhouse? – to decide whether spending an additional thousand dollars is worth it to you. But it’s worth remembering that that thousand dollars could buy an awful lot of spare batteries.