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Before further strip about how to over clock Intel Core i7 processor, first I want to introduce this processor technology and the difference with the previous technology.

IMC (Integrated Memory Controller) & Triple Channel DDR3The difference between the technology with the Core i7 technology, Core 2 Quad Duo/Core2 located in the IMC (Integrated Memory Controller). On core2 Duo / Core 2 Quad, IMC is embedded in the chipset (X38, X48, P45, and so forth). This causes the capacity of the memory throughput is highly dependent of the ability of the chipset. While the Core i7, IMC moved to the processor so that the chipset can work theoretically lighter throughput speed and bandwidth memory more quickly because there is no need to go through the chipset (Northbridge).Front Side Bus 1066, 1333 and 1600 MHz which is known to the processor core2 Quad Duo/Core2 switch into QPI (Quick Path Interconnect) on the Core i7. They also used a FSB speed of up to 1.6 GT / s of a 6.4 GT / s. This is because the speed of internal memory controller on the CPU is more effective than the Northbridge memory controller, not to mention the added implementation of the Triple Channel DDR3 Core i7 platform. Although, the benefit or effect the implementation of Triple Channel DDR3 is still not very significant in real applications.

Additionally, the Intel Core i7 return the Hyperthreading technology (HT) or also known as Simultaneous Multi-Threading (SMT). Total core Core i7 processor in the amount of 4 core units (core) and each core has a SMT, so that there are 8 total thread on a Core i7 processor.

QPI (Quick Path Interconnect)
QPI is the bus speed of FSB, the FSB is the data transmission path between the chipset, processor and memory, QPI simpler again. QPI is a data transmission speed of the processor to the chipset. When we know the previous Northbridge chipset as the processor, memory and the PCI-E, then the Core i7, chipset, known by the name of IOH (Input-Output Hub), which served as the input and output of the entire system.

Bclk (CPU Host Frequency) & CPU multiplier
Total clock frequency or a Core i7 processor is the result of multiple CPU Host Frequency (Bclk) with the CPU multiplier (CPU Ratio). For example, a processor Core i7-965 Extreme Edition has a speed of 3.2 GHz, this speed comes from the square 24 (CPU ratio) with 133 MHz (Bclk).

24 x 133 MHz = 3192 MHz (3200 MHz to be rounded)
To change this settingan in the BIOS (I use the motherboard GIGABYTE EX58-Extreme) to enter the sub menu MIT There are options Bclk frequency changes from 1 to 1200 and the CPU Clock Ratio from 1x up to 44x (depending on the type of processor that is used). Changes in the number Bclk will automatically change the frequency of total processor.

By changing the value of the CPU Clock Ratio from 24 to 28, the frequency will be of 3724 MHz processor speed from the standard 3200 MHz. Once again, over clocking the CPU Clock Ratio applies change only to the type of processor Core i7-965 Extreme. For Core i7-920 and 940 CPU Clock Ratio can not be changed to a higher number, because Intel has been locks the manufacturing CPU Clock Ratio. For Core i7-920 and 940, over clocking can only be done by changing the CPU Host Frequency (Bclk).
Please note, on the condition over clocked, the system stability must be considered. Instability can occur due to many things, one of which resulted in the QPI speed increase (if that was Bclk), other factors are the speed DDR3 and Uncore Frequency of follow up from the default.

QPI standard processor Intel Core i7-965 Extreme is 6.4 GT / s with Bclk of 133 MHz, 2.66 GHz Frequency Uncore and DDR3 at 1333 MHz speed. Note the picture above, if the increased Bclk of 150 MHz will be an impact on the frequency increase of QPI, Uncore and DDR3, the third component of this close and mutual dependence with Bclk. When one of the three components of this condition does not work in normal speed or at higher than standard and tolerance have been passed will cause instability in the system. Examples include system instability restart without any reason; can not go to the operating system, application errors and often many more. To overcome the instability over clocked system provided on the divider ratio or each component QPI, Uncore and DDR3.

QPI Bus value obtained from the square with the QPI multiplier Bclk (QPI Speed Link). On the condition Bclk running at speeds higher than standard (over clock), QPI Bus will also participate over clocked. QPI multiplier on the default condition for the Core i7-965 xe is 48, with Bclk 133 MHz, then 48 x 133 MHz = 6384 GT / s (rounded to be 6.4 GT / s). While the Core i7 processor and -920 Core i7, QPI Bus lower, namely 4.8 GT / s, obtained from the multiplication 36 x 133 MHz, meaning Core i7-920 and 940 have standard QPI multiplier of 36.

When overclocking via Bclk, where speed Bclk increased from normal conditions, for example, 150 MHz, QPI bus to be 48 x 150 = 7200 MHz (7.2 GT / s), the instability occurs in the condition of the system at this QPI Bus. To overcome these problems and improve system stability, can you can increase the supply voltage (voltage) at the VTT and PLL. You can do this from the BIOS, select the submenu MIT QPI PLL Voltage or QPI VTT.

NOTE: This voltage change can only be done when you use non-standard Intel cooling or 3rd party cooling with high performance. Increase voltage slowly and always test the system stability with the benchmark.
If the voltage is too risky, is another way that can be done is to change / lower the value of QPI Speed Link, provided some of the BIOS from AUTO multiplier, x36, x44, x48 and Slow Mode

In addition, with lower QPI Link Speed, and the total acquisition Bclk processor clock will also be higher because QPI Bus is still in the limit of tolerance.

Uncore Frequency
Frequency-related Uncore speed L3 cache and also have close ties with QPI and IMC. The higher Frequency Uncore performance will be high, although at the same speed the processors.

Frequency Uncore obtained from the square: Bclk x Uncore multiplier. In the standard conditions, Bclk 133 MHz, multiplier Uncore worth 12, so is Uncore Frequency 1600 MHz. Options Uncore multiplier provided in the BIOS from 12 to 30. If you want to increase the speed Uncore, you change the multiplier value Uncore to a larger number. Uncore limitation for cooling air or water-based (or heat sinks Fan Water-cooling) about 4000 MHz to 4100 MHz. Meanwhile, if using subzero cooling (Dry Ice, or Phase Change Liquid Nitrogen), Uncore no limitation on the number 4500 MHz to 4600 MHz.

Memory multiplier
Important factor in the latest Intel Core i7 over clocking is the memory multiplier. High-speed processor (read: clock), will have performance that is not balanced when it is not followed by a high-speed memory also. Here the memory multiplier role. Two processor systems with the same speed and same clock can vary in terms of performance because of differences in the frequency of memory.

Memory can change the multiplier from the BIOS options on the System Memory multiplier in the sub menu MIT. The multiplier from 6.0, 8.0, 10.0, 12.0, 14.0, 16.0 and 18.0. Suppose Core i7-965XE with Bclk running at 133 MHz standard conditions, speed of memory running at 1333 MHz. This means that the memory multiplier to work on 10.0. If you want to increase system performance without increasing the speed or CPU Ratio Bclk, increase only memory multiplier to multiplier number is higher. To achieve this, of course, required that is capable of DDR3 memory to run higher.

EXEMPLARY: A system based on the Intel Core i7 Triple Channel DDR3 memory 1600 MHz. When paired with the standard conditions, the BIOS will still recognize it as DDR3-1333, a working memory multiplier on multi 10. Would unused, memory speed as this is only running at 1333 MHz. To be able to take advantage of speed in 1600 according to the manufacturer standardization memory, memory multiplier can be changed to 12:00, so the speed of memory running at 1600 MHz (133 MHz x 12.0). Speed will also participate in memory has changed, when Bclk increased. Example Bclk on the speed of 150 MHz with the memory multiplier 12, the total speed of the memory will be a 150 Mhz x 12.0 = 1800 MHz.

Myth Voltage Overclocking Intel Core i7

the voltage is absolutely necessary for over clocking. Voltage is not only a role in the achievement of over clocking, but also the effect on the stability of over clocking itself. Myths such as the voltage memory voltage not more than 1.65 volt, because it can damage the processor is indeed true. When viewed from the Core i7 architecture itself, IMC is integrated on the processor, the impact of the excessive voltage memory IMC could damage the processor itself as well. This has happened before in AMD. To avoid that, the producers restrict the choice of AMD motherboard memory voltage to avoid damage to the processor in the IMC. Then how fate memory DDR3 memory that has the operational voltage above 1.65 volt? What can still be used? In the experiment, the author never uses voltage to 1.8 volt in the time period long enough and does not experience degradation in the processor or processors to die. In fact the influence of the voltage memory voltage does not directly affect the other, especially IOH voltage (voltage or chipset Core Voltage IOH) and QPI / VTT Voltage. Voltage IOH has a default value of 1.2 volt and QPI / VTT Voltage has a default value of 1.1 volt. In the experiment, the effect of increasing both the value of voltage stability is very helpful especially in the frequency of system memory and high memory voltage is high. The author set the Voltage IOH volt at 1:25 and QPI / VTT Voltage to 1.3 volt. Values obtained at this speed DDR3-2000 with a 1.74 volt voltage and stable running.

Conclusion
Over clocking the Core i7 platform is more interesting than the previous platform. There are obvious similarities with the over clocking on the AMD platform. Of course, because both platform use the same concept of architecture. Processor speed is no longer a totality in getting more performance, but other parameters such as the QPI Bus, Uncore Frequency and speed of memory, of course, contribute a significant role in improving overall performance. Over clocking results obtained from the ideal combination of processor speed, QPI Bus, Uncore Frequency, speed and memory. Component parts are closely related to each other, here’s a unique location for over clocking Core i7.

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