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The smartphone in your pocket is powerful. It is more powerful than a large amount of now-defunct supercomputers, and some modern ones, too. Another readily available fact is that “your cell phone has more computer power than all of NASA back in 1969 when it placed two astronauts on the moon.”
But modern smartphone microprocessors still lag behind the powerful processing available in your laptop or desktop. But isn’t it the same technology? Let’s take a look.
Mobile vs. Desktop
The numbers are similar, the names are too.
Mobile microprocessors use much of the same terminology as their desktop counterparts, but they are different. In fact, processors come in two classes: mobile and desktop. Furthermore, the “mobile” tag is a little misleading as it covers such a broad spectrum of devices; smartphones, laptops, internet of things (IoT) devices, and more.
Furthermore, the big players in the desktop chip-making market—Intel and AMD—don’t have much say in the smartphone microprocessor market. Both manufacturers sold their smartphone divisions, deciding against competing with Qualcomm, Apple, Samsung, and other mobile chip manufacturing giants.
That said, the Intel Atom CPU powers a handful of ASUS Zenfone models and there are rumors that they may re-enter the market during the upcoming 5G mobile generation.
Mobile and Desktop Processor Differences
There are a few key differences between smartphone processors and desktop processors that set the latter apart.
- CPU Architecture: System on a Chip
- Instruction Set Architecture: ARM vs. x86
- Power and Heat
1. CPU Architecture: System on a Chip
When we talk about a desktop CPU, we invariably are referring to that specific piece of hardware. A desktop CPU is the brain of the computer. When we talk about a smartphone CPU, the term “processor” more closely refers to the System on a Chip (SoC) architecture. So, how are they different?
Well, the SoC is a single chip roughly the same size as a desktop CPU, but it also houses a GPU (a graphics processing unit, another separate PC component), various radios, sensors, security layers, and device features. Remember, manufacturers pack all of this into a single chip. The following image shows the Samsung Galaxy S8’s Exynos 8895 SoC CPU capabilities.
That’s a lot of punch, requiring a lot of power. Consider that all of those components are separate hardware on a desktop, and we can move to the next section.
2. Instruction Set Architecture: ARM vs. x86
The second CPU architecture aspect to consider is the overall CPU design. Intel licenses their x86 CPU design to AMD and VIA Technologies. AMD are well known; have you ever heard of VIA?
Regardless, the Intel design dominates the desktop processor market. x86 CPUs are designed for high-end computational power, able to execute millions of instructions. And because your desktop computer draws power directly from the socket, the CPU can go wild, resulting in more powerful machines (as well as more heat!).
Smartphones are different. ARM design and license the majority of smartphone processors to manufacturers such as Qualcomm, Apple, and so on. But the key difference is knowing that an ARM smartphone microprocessor design favors both performance and battery life, rather than the outright power of a desktop CPU. Here’s why.
- ARM SoC CPUs use what is known as Reduced Instruction Set Computing (RISC). RISC instruction sets are smaller, require less energy to process, and complete quickly, freeing up system resources or allowing the device to “idle” to save battery.
- Intel x86 CPUs use what is known as Complex Instruction Set Computing (CISC). CISC instruction sets are vastly more complex, adding together strings containing multiple instructions.
In addition, all modern CPUs use something known as microcode.
Microcode is the type of internal CPU code that tells the CPU what actions to perform, breaking down operations into minute instructions. But microcode also works differently on RISC CPUs. Because RISC instructions are already comparatively small, breaking them down into smaller microcode operations is faster.
3. Power and Heat
CPU marketing tells us to look at the number of cores and the clock speed of the processor. But smartphone processor values differ in two ways: First, they do not correlate to desktop CPU measurements and, second, they are somewhat misleading because of this. The numerical values don’t illustrate the other important side of smartphone CPUs: power generation versus heat dissipation.
When the processor runs, it generates heat—a lot of it. A desktop CPU dissipates heat using a fan or heat sink; your smartphone CPU doesn’t have that same luxury. Also, the smartphone CPUs are packed into a confined space, sometimes in your hot pocket, next to your hot leg, on a hot day… getting really hot.
Smartphone CPU manufacturers know this and, as such, limit the overall speed with which the processor can run. A desktop CPU might advertise its consistent running speed, whereas a smartphone CPU is likely advertising its theoretical maximum capacity.
Take this example. The average Intel i7 CPU produces around 65-watts of heat; an ARM-based SoC CPU only produces around 3W—around 22 times less than the Intel chip. To be fair to Intel, we’re comparing a grape to a watermelon. The latest Intel Atom chips (designed for mobile and smartphone devices) have much better heat dissipation, as you would expect.
So, in theory, ARM could develop smartphone SoC CPUs that vastly increase clock speed—but your smartphone and its battery will critically overheat and die. And the good people at ARM really do not want that.
In some cases, smartphones are replacing desktop and laptop solutions. Recent handsets easily multitask, running multiple applications concurrently. Furthermore, the sheer range of apps available on Android and iOS means that finding desktop-equivalent apps is simple. Many of your favorite desktop apps have mobile equivalents too, like Microsoft Word.
And then there are integrated docking systems. Continuum was introduced by Microsoft with the release of Windows 10, allowing you to connect your smartphone to a screen. Similarly, Samsung’s DeX Docking Station connects to a screen and mirrors your smartphone display.
In both instances, you can somewhat rely on your smartphone as a productivity hub. However, those using resource heavy software will continue to rely on more powerful desktop solutions. (There’s heaps of hardware to help you out, too.)
Will Smartphones Ever Match Desktops?
In all honesty, it is difficult to say. Desktops should retain their dominance because smartphones are critically limited by their battery power and capacity. It is hard to imagine a time when smartphones are more powerful than the latest desktop CPU—but never say never.
The key thing to remember is that smartphone and desktop CPUs have different expectations and different goals. Measuring them accurately against one another isn’t always useful because of the vast differences in usage, as well as the continually shifting smartphone market.
Still unsure? Check out our jargon-busting guide to mobile processors before making your next purchase!