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verclocking is possible thanks to
two separate factors. Firstly, the
way PCs work necessitates that
the CPU is essentially controlled
by your motherboard. In other words, various
multipliers and system bus frequencies, as
well as features included within the CPU itself
such as Turbo Boost, directly impact your CPUs
frequency. Normally, you don’t need to worry
about any of this if your PC is operating at stock
speed, but if you so desire – and if your
particular CPU allows – it’s possible to tweak
these settings to increase performance.
It’s very similar to
tuning your car. By
adjusting settings
in the engine
management system
software, it’s possible
to boost horsepower and torque. Of course, if
your car’s engine isn’t able to handle the extra
load or is operating close to its limits, then you
could be drastically shortening its lifespan
or even end up destroying it immediately.
Thankfully, most engines are dialled back for
everyday use and so have plenty of headroom,
limiting the chances of a failure, and some are
even repurposed from a higher-performing
model that’s capable of a great deal more
power. This brings us to our second point
about why overclocking is possible.
When CPUs are made, unlike our car
engine example, they’re not created equal.
Microscopic imperfections that are introduced
THE CPU CANJUSTBE
REPACKAGEDASA MODEL
WITH FEWERCORES
easy target for overclocking the Intel Core
i7-8700K, yet the CPU was only rated to reach
4.7GHz at stock speed and even less than that
in all-core boost. However, we’re now seeing
9th-gen and 10th-gen CPUs with stock boost
frequencies of over 5GHz.
What this means is that there’s often a lot
of headroom in a CPU’s frequency anyway.
Moreover, if a CPU has been sold as a cheaper
model, it will be downclocked even more (to
provide clearer product differentiation) yet
there’s a good chance it’s still perfectly able to
reach the same peak frequencies.
In short, cheaper CPUs can often be
overclocked so that they perform similarly to
more expensive ones, which is one of the great
things about overclockingDOES OVERCLOCKING
REALLY GIVE YOU MORE
PERFORMANCE FOR FREE?
Overclocking your CPU can and will give you
more performance. Some CPUs will offer both
lightly and heavily multi-threaded performance
boosts once overclocked, while others may
only offer benefits in the latter if they’re not
able to push their single-core boost frequency
much higher. Games can also benefit and in our
recent CPU Labs test, everything from Intel’s
LGA2066 CPUs to AMD’s 3rd-gen Ryzen CPUs
saw increases in frame rates once overclocked.
However, whether you’d call overclocking a free
way to get more performance is debatable.WHAT IS OVERCLOCKING
AND HOW IS IT POSSIBLE?
in the semiconductor fabrication facility (fab)
when they’re made, mean some CPU dies
will either fail to work fully or even at all. In fact,
Intel recently told us that they’ve only had one
wafer in decades where all the dies ended
up in sellable CPUs. The margins for error
are so fine with ever smaller manufacturing
processes that even miniscule errors can have
big impacts.
The classic example of this is that an error
has made one core of a CPU unusable but the
rest work, so the CPU can just be repackaged
as a model with fewer cores. Other errors will
mean that some
chips require higher
voltages than others
to reach certain
frequencies, so they
may be downclocked
and sold as a slower chip. The ones that make
it through unscathed can, of course, be sold as
fully enabled top-end models.
Take, for example, Intel manufacturing the
Core i9-9900K. If the chip has an error, Intel
doesn’t just chuck these CPUs in the bin but can
repurpose them as cheaper models. If Hyper-
Threading requires too much voltage then it
could enter life as a Core i7-9700K. If one or
two cores are highly inefficient, it could become
a Core i5-9600K.
There’s also the fact that CPU designers
will create an architecture that can scale much
higher in terms of frequencies than is offered
at launch. For example, 5GHz was usually anGood-quality cooling is generally
required for overclocking, and it
can get expensive