Review: Apple Silicon, ARM and x86

 by James Heppell

This is a mid-range, 3 year old PC that’s capable of running most modern games and programs pretty well. Would it surprise you if I said the iPhone 12 has much better single core performance, and a similar multi-core? When the iPhone 12 came out it had better single core performance than any other consumer CPU; including the ones found in tablets, laptops, and desktops. In a couple of months, when the SD888 is released, Android phones such as the next Samsung and Oneplus flagships will have very similar performance.

So what’s the catch you ask? Well, due to space, battery and thermal constraints only the first 2-4 cores perform this well. The other 4 are a lot weaker, but more power efficient, designed to deal with background tasks and help out in heavily threaded workloads. So multi-core performance isn’t quite on par. But it easily could be, if only these CPUs were to be put in bigger chassis, such as laptops. Which just happens to be what Apple has done. Earlier this year they said that in the next 2 years, their entire Mac lineup will have transitioned to ARM SoCs1.

And on the 16 November they started that transition with the release of a new MacBook Air, Pro and Mac Mini containing their new M1 chip, a beefed up version of the A14 found in the iPhone 12. Benchmarks are already showing it to be the most powerful laptop CPU/GPU available, with much better multi-core then the iPhone 12 and slightly higher single-core, not to mention twice the GPU performance. With the same efficiency but lesser space, thermal and battery limitations than their smartphone counterparts, these laptops will probably put the entire Intel and AMD laptop market to shame, all while saving Apple money. Likewise ARM recently announced a variant of their upcoming A78 design called the A78C, designed for laptops and able to be used in 8 core configurations (with no weaker cores). Windows 10 has been available on ARM for a few years now, and the Surface Pro X (2020) is a pretty great machine, now that software support has matured a bit. But it’s still one of a kind which makes up a very very small portion of the Windows 10 market.

Why are these CPUs so much more power efficient? Well a lot of it comes down to the architecture. ARM CPUs have always been designed with power efficiency first and foremost and the architecture is very different to the x86 architecture found in almost all laptops and desktops. ARM (a Japanese owned British company) designs the mobile architecture, and other companies such as Apple and Qualcomm build CPUs with these designs. However just as big a part of the equation is that smartphones are where the innovation and funding is at. Since the first modern smartphones in 2007/2008, each year these phones have been getting 15-30% more powerful2, while using similar or less power. Intel and AMD x86 CPUs? Not so much. Intel’s 2014 4790k and 2017 7700k show a 9% increase in performance, with a 3% increase in power usage3. Not impressive. In the past couple of years AMD especially have been improving a lot faster, but still not at the rate nor the consistency of ARM designs. 

High end smartphones are already more powerful than most laptops, yet the TDP of a smartphone SoC is <5 watts. Most laptop CPUs are rated for ~15 watts, and desktop CPUs are commonly 65+ (the two in the graph are 95). When laptops start to use ARM CPUs to their full potential (native rather than emulated software), performance and battery life should go through the roof. Saying that, there is still one major weak point for ARM SoCs; the GPUs. The best ARM GPUs, while better than most laptops, are still an order of magnitude behind powerful desktop GPUs4, though you only have to look at the size and power usage difference to realize why.

iPhone 11 SoC | ~5 watts

M1 SoC | ~20 watts max system power draw

Nvidia RTX 3090 GPU | > 350 watts.

^ Peak power usage, eg when the system is under full load

1 - SoC stands for System-on-a-chip. An SoC contains the CPU, GPU, and more1.

The PC in the first photo is actually mine, with a-mazing cable management. Android devices, other non-Apple ARM devices (eg Surface Pro X) and the new ARM Macs have 8 cores, while iPhones have 6. Android phones usually have 4 performance cores, of which 1 is a ‘prime’ (better) core , while iPhones usually have 2 high performance cores. I mostly used iPhones as examples because they have a good naming scheme and are the most common phone brand in the UK. I have a Pixel 4A.