The 2013 MacBook Air: Core i5-4250U vs. Core i7-4650U
by Anand Lal Shimpi on July 4, 2013 8:00 AM ESTFinal Words
Simplicity permeates Apple from design and software all the way down to the purchasing experience. The 2013 MacBook Air offers only two choices of CPUs, and honestly for the vast majority of the population, that's all you really need. The default Core i5 1.3GHz (4250U) delivers the best overall battery life regardless of workload. Its performance is often somewhere in between a 2011 and 2012 MacBook Air depending on workload, although in some cases it's possible to see equivalent performance to an upgraded 2012 MBA. If you need more performance however, the 1.7GHz Core i7 upgrade (4650U) delivers. In most situations you get more than a 20% increase in performance, bringing the platform up to somewhere in between last year's 1.7GHz Core i5 and 2.0GHz Core i7 options. Once again, with the right workload you could even see performance as much as 20% better than a 2GHz Core i7 from last year. Although I didn't publish any results here, GPU performance seemed roughly unchanged compared to the Core i5 option.
The tradeoff in battery life is pretty easy to understand. In mostly idle workloads, I wouldn't expect any real degradation in battery life compared to the Core i5. Both configurations are equally capable of hitting the same max battery life number. More active workloads however will likely show a 15 - 20% decrease in battery life when paired with the faster CPU. It's possible that you'll see a larger drop with a very aggressive CPU-bound usage model, but at that point I'd assume that you'll probably want to be plugged in regardless of what system you're using.
In previous MacBook Airs, the choice of what CPU to buy was almost always a difficult one. Do you opt for the in-between upgrade or go all the way to the top? With this year's model, the decision is greatly simplified. If you want ultimate battery life regardless of usage model, stick with the base Core i5. If you need performance, the Core i7 upgrade is absolutely worth it. My personal choice would be for the Core i5, but that's because I tend to fall on the battery life side of of the battery life vs. performance fence when it comes to the MacBook Air. If the MacBook Air is going to be your only machine however, I can definitely make a case for opting for more performance.
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josephandrews222 - Thursday, July 4, 2013 - link
Anand--wonderful post. Care to speculate on the battery life and thermals for the Surface Pro 2?teiglin - Thursday, July 4, 2013 - link
Derp in last paragraph, first page: "The max clocks increase by almost 30%, as does the <s>increase in</s> L3 cache."Nothing really surprising here, but good to see it confirmed anyway!
Subyman - Thursday, July 4, 2013 - link
I wouldn't call the lower battery life a detriment, remember you have 20% less battery time, but you have 20% more processing speed, therefore you simply get the same amount of work done, but faster. For general surfing, there is no difference between the two but when working its faster.TheinsanegamerN - Thursday, July 4, 2013 - link
am I the only one more than a little disturbed to see temperatures of over 90c? thats awfully hot....MrSpadge - Thursday, July 4, 2013 - link
That's the price you have to pay for a flat laptop, without totally killing your ears.Paapaa125 - Thursday, July 4, 2013 - link
It doesn't matter what the core temperature is if it is within specs. And I guess 90C is.FwFred - Thursday, July 4, 2013 - link
This should only matter if the CPU was throttling due to temperature. As a consumer, you should be more concerned with skin temperature and fan noise.solmaker - Thursday, July 4, 2013 - link
Fantastic job on a fascinating topic. Two follow-up questions:1) Would i7 compare any different to i5 on the 11" model, given tighter thermals?
2) How will the comparison change under Mavericks?
My own thinking is that if Mavericks improves battery life by (say) another 25% across the board, 2013 MBA battery life will be so terrific (perhaps 12 hours even for the 11" i7 MBA) that 1/2 to 1 hour differences between models will seem like small change. At that point, processing speed would be the more important bottleneck, making the i7 look like an even better choice.
helloworldv2 - Thursday, July 4, 2013 - link
My guess is that Maverics increases battery life by 5% max and will inject a ton of new annoyances into OS X (like having to caffeinate everything that you want to keep on running even if you dare to take some other program into foreground). I read somewhere (maybe Gizmodo) that they didn't notice any battery life increase with Mavericks beta though..KitsuneKnight - Thursday, July 4, 2013 - link
A 25% increase across the board I'd say is incredibly unlikely. What seems far more likely, though, is making more workloads closer to being a 'light' workloads (so hitting closer to the advertised numbers in more cases).Timer Coalescing and AppNap will make it less likely for noisy apps to drain significant battery life when merely sitting in the background doing nothing (including background tabs of Safari, I believe... which'll hopefully include Flash applets on background tabs). This will help improve the likelihood of the CPU being able to hit lower idle states, saving more power.
In addition, Apple has put effort into making it easier to identify power hungry apps (which aren't necessarily CPU hogs!), both for end users and developers (the battery menu, Activity Monitor, Xcode, and Instruments all have an increased focus on identifying and addressing battery hogs).
But don't expect miracles like a 25% increase in battery life (I'd be *very* shocked if Apple was able to pull that off). I'd imagine it would be much closer to 5% in practice, but varying drastically depending on the actual workloads (anywhere from 0% if the system can't sleep at all to 50%+ in the extreme case of a horribly buggy app that AppNap neuters... with most clustering around the low end).