Now you have a new PC, should you overclock
it and what kind of results can you expect with good cooling?
Most processors, be they ADM or Intel, have
a good degree of extra headroom that can be unlocked by overclocking. In order
to overclock your system, you’ll need a motherboard that provides the necessary
features and suitably robust voltage regulation hardware, and in the case of
the new Socket 1155 Intel chips, a K-edition processor.
How To Overclock Your New PC ?
The clock speed on any processor is
determinate by the relationship between the base clock frequency and the
multiplier. In simple terms, a CPU’s frequency is calculated by multiplying the
base frequency and the multiplier together. To increase the CPU frequency, we
therefore simply have to increase the base frequency, the multiplier, or a
combination of the two. Although there are now motherboard-specific
applications that can overclock from within Windows, most of the ground work is
still done within your motherboard’s BIOS or UEFI setup menus. Not all chips
allow you to change both the base frequency and the multiplier, restricting you
to either one or the other. On most Intel Sandy Bridge CPUs, both are
effectively locked, making overcloking impossible. This means the days of
taking an entry-level Intel chip and coming away with high-end performance have
finally come to an end.
Different chips have different overclocking
headroom, but usually you can unclock a decent amount of extra performance.
Provided you have decent cooling, your chip will normally run out of steam long
before it gets too hot, meaning you can unlock extra headroom by injecting some
extra voltage. When we overclock a CPU, the amount of power required for it to
maintain a steady and stable stream of information also increases, so by
feeding a chip a higher voltage we unlock extra clock speed, albeit with a
corresponding increase in head output. Different chips have different ceilings
or voltage, which you should not exceed, but as a rule you should not increase
the voltage of your processor by more than 10% without some serious extra
cooling. Rather than relying on your motherboard to tell you how much voltage
your chip is using by default, check this reading when under load in Windows by
using CPU-Z, a free piece of software downloadable from www.cpuid.com. Take a recording of this and
you can then gauge how much extra voltage you can safely feed your chip when
shooting for the highest stable clock speed.
When overclocking, it’s invariably better
to shoot for small incremental increases and test for stability as you go
rather than trying for a huge increase in speed straight off the bat. Only ever
overclock on a system where you have critical data backed up, because a
processor that isn’t operating with full stability can result in corrupted
data.
Regardless of your CPU architecture, the
same tools are needed when overclocking. First of all, you need a program to
monitor your CPU’s temperature, our favorite of which is CoreTamp. Secondly,
you will need an application that can show the real-time clock speed and
voltage – the aforementioned CPU-Z. Finally, you need a piece of software that
can stress the CPU at 100% load while checking for computation errors. One of
the most effective programs for this very purpose is Prime 95, a number
crunching application that stresses the CPU by calculating very large prime
numbers. The results are then compared to a record known to be correct and any
discrepancy is reported as a failure. Prime 95 is particularly useful, because
it has a buit-in torture test that will put all available threads to 100%
utilisation.
Overclocking AMD Chips: FM1
Socket FM1 chips are multiplier-locked with
the exception of the Black Edition A6 and A8 variants. Fortunately, we can
still overclock these processors by raising the base frequency with the BIOS.
The stock base frequency is 100MHz, which good motherboards will allow you to
increase to 150MHz or more. This increase will normally allow you to hit the
ceiling of these chips’ capabilities, which seems to be between 3.5 and 3.9GHz
depending on the quality of your sample. You should treat a voltage of 1.5V or
so as an absolute maximum without extremely elaborate cooling.
If you have a Black Edition chip, you can
make a life a lot easier by simply adjusting the multiplier to the maximum at
which it remains stable. You can then fine tune your setup to squeeze out those
final few megahertz by upping the base multiplier at the same time.
Overclocking AMD Chips: AM3+
ADM Fusion – Family of APUs
All the Bulldozer FX chips currently
available are Black Editions, meaning you simply need to concentrate on the CPU
voltage and the multiplier. As with Socket FM1, you can also fine tune your
results with an increase of the base clock. Unlike socket FM1 chips, you are
likely to hit a thermal boundary before you exhaust the capabilities of the
chips. Most Bulldozer chips top out at around 4.5-4.8HHz, putting them within
shooting distance of the speeds obtainable by Socket 1155 Intel chips. They run
a lot hotter, however, so you’ll need a very effective air cooler or water
cooling to unlock the best from these chips. We had our best results at an
actual voltage of between 1.4 and 1.45V for these processors.
Overclocking Intel Chips: 1155
Only K-edition chips can be significantly
overclocked from the second-generation Core i3, i5, i7 chips. Currently, this
means you will need a Core i5 2500K, an i7 2600K or an i7 2700K, otherwise
you’re locked at your processor’s default frequency (or within a couple of
multiplier increments of it for turbo-technology-equipped non-K edition Core i3
or Core i5 processors). By internalising the clock generator to the 6 series
chipset, the previously adjustable base clock is now under Intel’s direct
control and has been locked down, meaning we’re fully reliant on adjustable
multipliers. Fortunately, the K-edition chips are mighty, if expensive, with
many capable of speeds between 4.6 and 5.0GHz depending on the quality of the
chip. A ,aximum voltage of 1.45V should be adhered to when overclocking these
chips, and you’ll find the i7 variants run hotter than their ị brethren.
Overclocking Intel Chips: 2011
Intel core i7
Intel’s current Socket 2011 line-up
consists of only three processors, two of which are six-cored K-edition
variants. These are unlocked like their Socket 1155 relatives. The third and
final chip is a quad-core non-K edition, which is what Intel calls ‘partially
unlocked’, and can therefore only be overclocked by a couple of multiplier
increments, as with other second-generation Core i5 and i7 chips. The six-cored
chips run very hot indeed and therefore need serious cooling to maximise their
potential, as with ADM’s eight-cored Bulldozer. Assuming you have this, you can
expect to max out at around 4.6 – 4.7GHz with a peak voltage of around 1.45V.
