About Overclocking of computer

The prospect of overclocking a computer system can be intimidating for a computer newcomer, to say the least. The idea is simple enough; make the computer's processor run faster than its stock speed to gain more performance without paying for it. The execution of this idea though, can be anything but simple.
Successful overclocking is as often a matter of 'what you know' as 'what you have'. Understanding the maze of hardware dependencies and tweaks that can make the difference between a successful overclock and total failure is a demanding practice.
What Does Overclocking Do?
Overclocking a computer's processor or memory causes it to go faster than its factory rated speed. A processor rated at 2.4GHz might be overclocked to 2.5GHz or 2.6GHz, while memory rated at 200MHz might be pushed to 220MHz or higher. The extra speed results in more work being done by the processor and/or memory in a given time period, increasing the overall computing performance of the PC.
Can Overclocking Damage Computer Hardware?
Yes, but it's typically unlikely. Generally speaking, when computer hardware is pushed beyond its limits, it will lock up, crash or show other obvious errors long before it gets to the point where the processor or memory might be permanently damaged. The exception to this is if extreme voltages are used when attempting to overclock, but since most motherboards do not support extremely high voltages, and neither does this guide, it's not likely to be an issue.
For older processors, heat is also a factor worth keeping a close eye on. Modern processors have thermal sensors which will slow down or shut off the PC, but older CPUs do not necessarily feature these safety devices. The best know example of this is the AMD AthlonXP (socket A/462), which was famous for burning itself up in less than 5 seconds if the heatsink was not installed properly (or at all).
The Purpose of Overclocking
The most obvious reason to overclock a computer system is to squeeze some additional performance out of it at little or no cost. Overclocking the processor and system memory can significantly boost game performance, benchmark scores and even simple desktop tasks. Since almost every modern processor and memory module is overclockable to at least a slight degree, there are few reasons not to attempt it.
Important Overclocking Concepts
The following terms will be used throughout this guide, so it's important to get a good grasp on them now.
FSB (FrontSide Bus): The data bus that carries information from the processor to the main memory and the rest of the system. A processor's internal multiplier multiplied the FSB speed of the system = that processor's speed in MHz or GHz.
Increasing the clock speed of the FSB (and thus the speed of the memory and the processor as well) is the most common and effective way of overclocking a modern computer.
AMD Athlon 64-based systems do not use a conventional FSB since the memory controller is built right onto the processor's core instead of being located in the motherboard's core logic chipset. Instead, a value called motherboard clock speed is used to determine the speed of data transfer between the processor and the memory. For the purposes of this article, FSB and motherboard clock speed are interchangeable terms.
Internal Multiplier: The ratio of a given processor's speed (in MHz or GHz) as compared to the FSB (Frontside Bus) speed of the computer system it is installed in. A processor with an internal multiplier of 16x installed in a system with a FSB of 200MHz would run at 3.2GHz internally, since 16 x 200MHz = 3.2GHz. Most modern processors are 'multiplier locked' to some degree, meaning that their internal multiplier cannot be changed (or at least increased). This in turn means that increasing the FSB speed of a system is the only way to overclock the processor.
Memory Divider: Most modern Intel Pentium 4 and AMD Athlon motherboards allow a memory divider to be set. This divider allows the system memory to run slower than the actual FSB speed. By default, FSB speed and memory are usually set to a 1:1 ratio, meaning that increasing FSB speed (by overclocking) increases memory speed by the same amount. Most 'generic' system memory is not built for overclocking and thus may not be able to take the level of overclocking that the processor or motherboard can achieve.
The memory divider allows users to mitigate this problem by reducing the speed increase of the memory relative to that of the FSB and the processor. Setting a 5:4 memory divider would mean that memory speed increases at 4/5th the rate of the FSB, for example.
Reducing the relative speed of the memory does result in a slight decrease in performance as compared to the default 1:1 ratio between FSB and memory speed, but it may help users with generic memory achieve a higher overclock.
Stock Speed: The default or factory speed settings of computer hardware like the processor, memory and motherboard. With the processor, stock speed refers to the clock speed in MHz or GHz of the processor. With the memory, stock speed refers to the highest standard memory speed that the memory module is rated for (PC3200 DDR memory has a stock speed of 200MHz, for example). In the case of the motherboard, stock speed refers to the default speed at which the processor and memory work together, the FSB speed.
To tie this all together, say a motherboard has an Athlon XP 3000+ processor installed (stock speed 2.1GHz) which uses a FSB speed of 166MHz. A PC3200 DDR memory module (stock speed 200MHz) is installed. Since the processor requires a 166MHz FSB, the motherboard will set the memory speed to 166MHz which becomes its stock speed with the current configuration.
Core/Memory/Chipset Voltage: These three voltage values represent the amount of electrical power being fed to the respective components. When a processor, memory or motherboard is made to run faster due to overclocking, more voltage may be required in order for that component to run stably. With this in mind, voltage adjustment is one of the most important principles of overclocking.
If an overclocked computer becomes unstable, increasing one or more of these voltage settings by a very small amount (0.05V to 0.1V) can often mean the difference between an unbootable system and a stable overclocked one. That being said, it is important to make some distinctions with respect to voltage adjustments; more voltage does not necessarily mean faster speeds, rather minor increases can help improve stability. Computer circuits are designed to operate within very specific electrical ranges, and drastically increasing the electricity being supplied to a chipset will raise temperatures, and potentially damage it.
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