How many ‘cores’ does a smartphone need?

Samsung Galaxy A5 2017

What does it mean when smartphone companies boast about multiple ‘cores’ in a mobile phone? And do I really need eight of them?

Matthew K, via email

Right. The short answer to this is: no, you don't need eight cores in a smartphone, but it sure does help things along.

Now, let's look into the why of that, and what exactly 'cores' are. Ready for things to get A BIT COMPLICATED? Because things are about to get A BIT COMPLICATED.

What are cores?

The CPU - central processing unit - in any gadget is made up of several cores. So, to review:

Cores = little processor bits

Dual-core processors have two cores, quad-core processors have four cores, and so on and so forth.

The processor, by the way, is the thing that drives the phone. The more power in the processor, the more stuff you can do with your device, and the faster it can do it. Each core has a set amount of potential power in it.

More cores = more power, right?

Yes, but only up to a point. The more cores you've got, the more raw processing power there is.

However, once you get beyond quad-core, it all works a bit differently. The majority of octa-core processors are actually two quad-core processors that work together. Instead of them all driving the phone at once, the cores take it in turns to helm the wheel. Usually, the processor does this by using:

a) a low-powered set of cores, for normal use; and

b) a high-powered set of cores, which only kick in when you want to do something more complex (games, loading big web pages, recording video, etc.).

A similar setup often works with hexa-core processors too - which are made up of one quad-core and one dual-core chip. (Not all octa- or hexa-cores do this, though - it's just the most common setup. Qualcomm has a great explanation of how it all works in this article.)

An octa-core processor isn't twice as powerful as a dual-core one, in other words. It's more power efficient, because it only uses its full power when it needs to. And yeah, it's usually a bit faster.

iPhone 7

So… do I need an octa-core processor?

Well, here's the thing. There's really no need for uber-powerful octa-core processors most of the time. The majority of tasks you do on a smartphone - flicking through apps, sending texts, using the web, reading emails, and so on - don't require much power at all. And engaging the uber-powerful processors all the time is a huge, huge battery drainer.

What the nature of the octa-core processor means is that you can engage the more powerful cores when you want to do something more intensive - like gaming or watching HD videos - and they'll handle it smoothly. The rest of the time, they hang back and leave your battery alone.

Having more cores in a processor does make a difference to how a smartphone performs. Buuut most tech experts (techsperts?) agree that, as far as everyday usage goes, the number of cores in a gadget isn't as beneficial as how fast each of those cores are. It's also not as important as the chip's architecture, and how the processors, memory, and GPU work together. The same kind of processor can work very differently in different models of phone.

So, there's certainly an argument that you don't need eight cores in a phone, no. Almost everything can be done just fine - if a little bit slower - with, say, four cores. Rocking an octa-core setup just means that the phone is better at handling the more intensive stuff.

Generally speaking, an octa-core processor will be useful to you if:

  • You want to use your phone for intensive tasks sometimes, such as playing games, streaming from the web, photo editing, or recording video; or
  • You intend to have this phone for a few years and want something a bit future-proof.

Octa-core chips are surprisingly common these days, especially in top-end Androids. They're really best thought of as a 'nice-to-have' or an 'oh, handy, it's octa-core' rather than an 'absolutely essential, I refuse to buy a phone that isn't octa-core'.

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