At one point, our computers had a central
processing unit (CPU) with a single core. These days, most
CPUs you’ll come across are dual core, quad core, or even octo
core. We’ll explain exactly what a core is, dual core vs quad
core, and how this all impacts your real-world computer usage.
The answers aren’t just helpful for leaning more about your
computer — you may have to choose between a less-expensive CPU
with fewer cores or a more-expensive CPU with more cores when buying
a laptop, tablet, or even a smartphone. Knowing the
difference between dual core vs quad core CPUs – and what it means
for you – will help you make smart decisions when purchasing new
What Is a Core?
Each CPU “core” is actually a separate central processing unit,
which is the part of the CPU that actually does the work. For
example, a dual-core chip may look like a single CPU chip, but it
actually has two physical central processing units on the chip.
Additional central processing units allow a computer to do
multiple things at once. If you’ve ever used a single-core CPU and
made the upgrade to a dual-core CPU, you should have noticed a
significant difference in how responsive your computer is.
For example, let’s say you’re extracting an archive file and
browsing the web at the same time. If you had a single-core CPU in
your computer, web browsing wouldn’t be very responsive. The
single core would have to split its time between web browsing and
file-extraction tasks. If you had a dual-core CPU with two cores,
one core would work on extracting the file while the other core
did your web-browsing work. Web browsing would be much faster and
Whether you’re doing multiple things at once or not, your
computer is often doing system tasks in the background and you can
benefit from additional cores to keep the operating system
responsive. Applications can also be written to take advantage of
multiple cores. For example, Google
Chrome renders each website with a separate process. This
allows Google Chrome to use different CPUs for different websites
rather than using a single CPU for all browser-related tasks.
Clock Speed vs. Cores
CPUs have a clock speed – think of it as how fast the CPU does
work. (That’s actually an imperfect analogy as the truth is a lot
more complicated, but it will have to do for now.)
For example, Intel’s Core i5-3330 processor has a clock speed of
3 GHz and is a quad-core processor, which means it has four cores.
All four cores in this Intel i5 processor are each running at 3
Doubling The Cores Doesn’t Double The Speed
Many computer programs are single-threaded, which means that
their work can’t be divided across multiple CPUs. They must each
run on a single CPU. This means that doubling the cores won’t
double their performance.
If you have a single-threaded application running on a 3 GHz
quad-core CPU, that application will run at 3 GHz — not 12 GHz. It
will use one core and the other three cores will sit idle, waiting
for other tasks to perform.
Writing properly multithreaded applications that can scale across
several CPUs at once is actually a difficult problem in computer
science. It’s becoming a more crucial problem, as the
future looks to be computers with more and more cores
instead of fewer cores at faster and faster speeds.
Some applications can take advantage of multiple cores. Google
Chrome’s multi-process architecture allows it to perform actions
across several different cores at once. Some computer games can
divide their calculations across multiple separate cores at once.
However, most of the applications you use are likely
single-threaded. A quad-core CPU won’t run Microsoft
Office twice as fast as a dual-core CPU. If all you do is
run Microsoft Office, the performance might be extremely similar.
More cores help if you’re looking to do more at once or if you
have a multithreaded application that can take advantage of them.
For example, if you’re running several virtual
machines while encoding video, extracting files, and doing
other CPU-demanding things on your computer, an octo-core CPU may
be able to keep up while even a quad-core CPU may stumble under
Dual Core, Quad Core & More
Phrases like “dual core,” “quad core,” and “octo core” all just
refer to the number of cores a CPU has:
Dual Core: Two cores.
Quad Core: Four cores.
Hexa Core: Six cores.
Octo Core: Eight cores.
Deca Core: Ten cores.
Controlling & Monitoring Cores
You can actually control which running programs can use a core
from the Windows task manager. Right-click a process on the
Processes pane and select Set Affinity.
You’ll be able to select which physical CPUs (cores) the
application can run on. You shouldn’t need to tweak this most of
the time, although it can be helpful when you want to restrict a
demanding application to certain cores or avoid bugs in old PC
From the task manager, you can also use the Performance tab to
view the usage of all your CPU cores.
Intel CPUs use a technology referred to as “hyper-threading
technology.” With hyper-threading, each physical core presents
itself to the system as two logical cores. In the screenshot
above, we’re not using an octo-core CPU – we’re using a quad-core
CPU with hyper-threading.
This improves performance to some degree, but a quad-core CPU
with hyper-threading is nowhere near as good as an octo-core CPU.
You still only have four physical cores, although some tricks
allow them to do a bit more work at once.
Have a question of your own about how technology works? Ask us on MakeUseOf
Answers! This article was inspired by several good
questions on MakeUseOf Answers.
Image Credits: Nao lizuka on Flickr, Installing computer CPU on a motherboard via
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