M4 efficiency is stunning. First machine I've tested getting over 5 Gflops/W with HPL, and in fact it goes beyond 6 Gflops/W... with fan only spinning up to a quiet 2500 rpm.

Maybe this is why Qualcomm abandoned their marquee Dev Kit—it is thoroughly trounced by M4.

@geerlingguy all you have to do is turn it upside down to get the power button in right place and cover up the apple logo. You also get more cool air when its sucked in from the top.