Which processor is better: 2017 MacBook Air's Core i5 vs 2017 MacBook 's Core M3 Kaby Lake version?


Junior Member
Oct 4, 2017
I was reading about processors, but I’m a bit confused. I read that Core M processors are less powerful than full Core i processors because they are designed for mobile devices while the full Core i’s were designed for laptops and desktops, so I initially took that as the Air's Core i5 being more powerful than the MacBook's Core M.

However, the 2017 MacBook Air’s Core i5 is from the Broadwell generation while the 2017 MacBook’s Core M3 is from Kabby Lake.

From what I understand, Kabby Lake chips are supposed to be faster and more efficient than those from older microarchitectures, so I guess that should make the MacBook better than the Air? Then again, Core M processors are designed for mobile or ultra-thin devices which typically have less processing power, I think?

I wonder which one is actually better, especially when multitasking or using more resource-demanding programs? Will there be a significant difference between the two?


Mar 11, 2000
Yes, the MacBook has a brand new 2017 m3, but the Air has a 2-year old i5. They often bench in the same ballpark, but the Air will be able to maintain that speed over time, as it has a fan, whereas the MacBook m3 may decrease in speed over time with sustained load due to throttling, as it has no fan.

However, the m3 also has some hardware decode support that the Air's Broadwell i5 doesn't have. That means if say you wanted to play 10-bit 4K HEVC, the m3 can do it easily and the Air can't do it at all. On the m3 it will be smooth as butter, and on the Air it will be stuttery mess.

So overall, I'd say the m3 is the superior chip, with the only caveat is that it can lose speed as the machine heats up because it has no fan. That said, In my Cinebench testing, the m3 only lost about 4-5% performance over 25 minutes of full load. My testing consisted of running Cinebench repeatedly and recording the score achieved with each run. The first run was 264, and after 10 runs (~25 mins) it was down to 253.


Above are the scores for my m3 and someone else's i7. Note that only the first 10 runs are valid. In run 11, I had moved the MacBook m3 to a different spot on the counter, and the performance increased, presumably because that part of the table was cooler. For the MacBook i7, the person got a phone call in run 11 so the performance that run dropped significantly.

For Cinebench, the MacBook Air's 1.8 GHz i5 gets 277, which is about 5% faster than my m3.

Interestingly though, the MacBook only gets around 6500 in Geekbench 4, whereas the m3 gets 7000, which is about 8% faster.
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