About the CPU of the new 12-inch MacBook

Apple just released its Early-2016 iteration of the 12-inch MacBook. In addition to the new pink (rose gold =_=) option, they swapped the processor from Broadwell Core m to the new Skylake Core m, namely the Core m3, m5 and m7, as shown below.


One interesting point about this is that the price of Core m3 and m5 are identical, despite the ~$200 price bump when buying from Apple. Although it is possible that Apple managed to force Intel to drop the price of Core m3 when they were buying them from Intel, it is more likely a pure marketing strategy due to the irrelevancy between price and cost.


Also according to Intel’s ARK database, the base frequency of these processors (900MHz, 1.1GHz, 1.2GHz)  are different from what Apple claimed on its website (1.1GHz, 1.2GHz, 1.3GHz), but the Turbo Boost frequency stayed the same. Considering the massive Turbo Boost headroom of Core m processors, it is possible that Apple clocked them 100MHz higher due to its confidence on the MacBook’s thermal capacity.


Another interesting point is about the TDP. While the TDP and the maximum configurable TDP of these processors are identical, the minimum configurable TDP of Core m3 is slightly higher than its brothers.

One big feature of the Core m lineup is its variable TDP. The manufacture could change the processor’s target TDP to adapt to the product’s form factor and thermal design, thus altering the performance thereof. Because of this flexibility, the “Core m” brand couldn’t make any guarantee on the performance’s side, for a higher-clocked Core m3 with better cooling can perform well better than a poorly-cooled Core m7.

In this regard, although the minimum TDP of Core m3 is higher than m5 and m7:

  • it won’t affect shit,
  • actually this might just be a typo from Intel.


As Intel stated, all three of these Core m processors support video output at 2160p@60Hz via DP or eDP. But when using HDMI as the output tunnel, limited by HDMI 1.4, it can only output video up to 4K@30Hz.


But according to Apple’s tech specs, the 12-inch MacBook can only output video at up to 2160p@30Hz. It’s safe to say that the MacBook “can’t work with” a 4K monitor because almost no one want there screen refresh rate to be limited to 30 Herts. Here’re three possible causes:

  • It’s limited by the Intel HD Graphics driver in OS X,
  • Apple doesn’t sell USB-C to DP adapter. What Apple offers is a USB-C to HDMI adapter (along with a USB-A female port and a USB-C female port for power), which,  limited by the data rate of HDMI 1.4,  can only achieve 4K@30Hz. However technically, it is possible to achieve 4K@60Hz via the USB-C’s native support of DisplayPort 1.2. Although it remains to be tested.
  • The USB-C port that MacBook utilizes is of USB 3.1 Gen-1, with maximum data speed of 5Gbps, whereas a typical 4K@60Hz video signal (with overhead) is at about 15Gbps, far exceeding the capacity of USB.