Lesson 01 - Introduction to Overclocking
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In these videos we are going to show how to overclock a socket 1366, Core i7 920 CPU. We will take this CPU from its stock speed of 2.66GHz first up to 3.2GHz and will gradually increase its speed all the way up to 4GHz. You will see every step along the way so you can apply the same process to your Core i5 or Core i7 CPU and maximize your computers performance.
Before we get into how to overclock a Core i5 or i7 CPU we need to understand some basics of how a CPU's speed is determined.
Frequencies and Multipliers
When
you see that a Core i7 920 CPU runs at 2.66GHz, that speed is derived
from a base frequency, also referred to as the Base Clock, or BCLK
times a multiplier. All Core i5 and Core i7 CPUs have a standard base
clock of 133MHz. In the case of the Core i7 920 the multiplier is
20x. If you multiply 133x20 you get 2660 or 2.66GHz.
To overclock the CPU we have to
increase either the BCLK or the multiplier. With the exception of the
Core i7 975, all other Core i5 and Core i7 CPUs can not increase their
multipliers beyond the stock setting. You can lower the multiplier,
but increasing beyond the stock settings is not possible, except in the
case of using Turbo mode which we will talk about later.
The
Core i7 975 has a unlocked multiplier which means it can be increased
beyond its stock setting. Leaving the base clock at standard you can
simply increase the multiplier to find the maximum overclock the CPU
can handle. This is the easiest Core i7 to overclock, but it's also the
most expensive at $1000. What we're going to do is take the cheapest
socket 1366, Core i7, the 920 and show you how to overclock it by
increasing the base clock. We will make it faster than the 975 for
$700 less. Again, these methods will work with all Core i5 and Core i7
CPUs.
The base clock also effects three other frequencies. These
are the Quick Path Interface or QPI, the uncore, and memory
frequencies. The QPI is what connects the CPU to the rest of the
motherboard. The uncore is everything on the CPU that is not the CPU
cores. This includes the cache on the CPU and the memory controller on
the CPU. The memory frequency is just what it sounds like. It's the
frequency the memory runs at. Typically this is 1066, 1333, or 1600MHz.
By
increasing the base clock, we will be increasing the frequency of these
other components. This could result in overclocking these components
to the point where they cause the system to be unstable before the CPU
can reach its' maximum overclock. Fortunately, each of these components
have their own multiplier that we can set. We will lower these
multipliers so the QPI, uncore and memory frequencies stay within their
limits to keep the overclock of the CPU stable.
Voltages and Temperatures
When
raising the frequency of the CPU cores, QPI, uncore and memory we will
eventually reach a point where one or more components become unstable.
To combat this instability, we will increase the voltage to one or more
of the components. The increased voltage will help stabilize the
component.
There are four voltage settings we can change to help
improve the stability of the overclock. These are the Processor core
voltage, which is the voltage going to the CPU cores themselves, the
uncore voltage, which is for the QPI and CPU cache, the memory voltage
which is the voltage going to the memory itself and the CPU Phase
locked Loop or PLL which is a control system for the CPU.
By
raising the frequencies and voltages we will also raise the temperature
inside the CPU. Depending on the cooling you have for your case and CPU
as well as the ambient room temperature, at some point the increased
heat may be too much for the CPU to handle. To push the CPU further we
would first need to improve its cooling.
In the next lesson we
will run some tests on our CPU with stock settings to get a baseline
for how well it is being cooled and performing.
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