Overclocking is the process of making a computer component run at higher clock rates rather than the standard clock rates.It is basically of three types Processor , Graphics Card and RAM .In the following article overclocking of a processor is shown by taking amd 2800+ as the base. Processor overclocking is the most common type of overclocking done by Pc users these days.

It is achieved by manipulating the CPU Multiplier and the FSB(front side bus of the motherboard).Increasing the FSB is your main aim as it allows you to take more juice out of your CPU. While Overclocking several measures have to be taken , foremost being that there should be enough power supply to deal with the increased FSB.

Second consideration that should be kept in mind is about the temperature of the CPU.You dont want your CPU to run at 90C as it will result in burning of your motherboard and nothing else. In order to overclock you should know how the bus speed is calculated. All processor speeds are based upon two distinct factors, bus speed and multiplier. The bus speed is the clock rate at which the CPU communicated with the memory and I/O devices. The bus speed is commonly measured in MHz. The multiplier is the multiple that the processor will run at compared to the bus speed. Lets explain this by taking an e.g. of a P4 machine.

133 MHz x 18 multiplier = 2394MHz or 2.4 GHz

Some more examples are provided below.

CPU Model Multiplier Bus Speed CPU Clock Speed
Athlon XP 2500+ 11x 166 MHz 1.83 GHz
Athlon XP 2800+ 12.5x 166 MHz 2.08 GHz
Athlon XP 3000+ 13x 166 MHz 2.17 GHz
Athlon XP 3200+ 11x 200 MHz 2.20 GHz

For overclocking your processor you should have Everest and Prime95 installed on your pc and Memtest86+ burnt on CD .Your next step is to open
Everest, go to Motherboard then SPD and just below CPUID, look at the Real Clock Value and take it down. Then look at your HyperTransportClock value.

Now you have on SPD which is just below Memory on the left hand menu. Take a look at the Memory Timings part, look at the values that your Ram can operate at and take them down.

Now next step is to restart your pc and enter your BIOS. After entering the BIOS go to that part which allows you to select the FSB of your CPU (different across different motherboards). The most basic way to overclock your CPU is to increase it in short increments.

The value should be increased by multiples of 5.So the first value after increment should be 205. Save and exit the BIOS and then restart the computer. Make sure your pc is set to boot from CD and have Memtest86+ disc in the drive. After restarting the Memtest will start. Make sure that you dont abort in between of any test as the errors are shown in the later tests. I recommend running the whole program just to guarantee absolute stability. After all the tests are complete restart your pc and boot into windows , open Everest in the background and start prime95.In Prime95 choose the Torture Test option and let it run for a few minutes.

If Prime95 was able to run good for a long time and no errors were found, then press escape key and congrats, you have just overclocked your PC.Go back to the bios and increase it a further 5 MHz, to 210. Then run memtest again, if it still passes then boot into windows then use the Stress Test on Prime95 again. Continue this until either Memtest or Prime95 returns an error, and then revert back to the last value that passed both tests.

There are lots of chances that the first test i.e. Memtest fails. This is because your ram has reached its absolute maximum operating frequency. To resolve this problem, we setup a divider in between the CPU and RAM ratio. In order to this restart your pc and go into that part of your Bios that lest you modify the RAM timing.

Once you have found that you need to change it from 200Mhz.Change it to the next lowest value, mine is 166 MHz. Now, because we are going to further increase the FSB, the HyperTransportClock is going to also increase even more. So in order to combat this, we lower it in the BIOS. I'll change mine from 800 MHz to the next lower value which is 600 MHz for me.

Now increase the FSB up to the next value i.e. 205 MHz. If it works, then go back to the Bios and keep trying the values until you get an error in either memtest or Prime95. If once again Memtest returns an error before Prime95, you can just knock the Memclock Index Value down to the next value i.e. 133mhz. Using this technique you will be able to safely determine the maximum speed for your processor to run at, as long as you run Memtest and Prime95 to verify that there are no problems. Once Prime 95 returns an error, it means that is the "max" for your CPU, but there is a way to squeeze a bit more out of it, but that method will produce a bit more heat.
Go into your BIOS and increase your CPU VCore temp. This will produce more heat, but will also give the CPU a bit more room to increase the FSB.

In this article till now we have talked about how to overclock the CPU.However there are lots of factors which decide whether the CPU can be overclocked or not. The first and foremost is a motherboard and chipset that has a BIOS that allows the user to modify the settings. Without this overclocking isn't possible as you won't be able to change the clock rates i.e. FSB.These days the trend is that most of the computers offered by major brands disable this option, as a result overclocking also gets disabled. Due to this people interested in overclocking tend to buy specific parts and build their own systems or from integrators who sell the parts that make it possible to overclock.Despite the chipsets ability to change the clock rates other components such as RAM should be able to handle these changes. So if someone tends to overclock the CPU synchronously with the RAM then the RAM should be able to work at higher clock rates.

Another important consideration which has to be taken regarding overclocking is the voltage. Every computer part works for a specified range of voltages. It is possible that while overclocking voltage goes out of range for a particular part and hence the pc becomes unstable. When overclocking the bus or multiplier speeds, the signals are more likely to get interference. To combat this, one can increase the voltages to the CPU core, memory or AGP bus. There is a particular limit on the amount of additional voltage that can be applied on the CPU.If too high voltage is applied then the circuits inside the CPU can break or melt down easily.

The main problem which arises as a result of overclocking is heat. Today's high-speed computer systems already produce a large amount of heat. Overclocking a computer system just compounds these problems. Hence anyone interested in overclocking should first research on the different cooling options available. Cooling can be of the form of CPU heat sinks and fans, heat spreaders on memory, fans on video cards and case fans. Key to good cooling performance is the clean airflow of hot air-Cooling is of two types air cooling and liquid cooling. Air cooling is the cooling described above. Liquid cooling is far more complex than air cooling. However liquid cooling provides a higher performance and generates less amount of noise. The chances of short circuiting increases when liquid cooling is used as decent amount of liquid flows between the pipes of the cooling equipment which is spread all around the cabinet.

Overclocking is a very tricky process and should be carried out extremely carefully. It is not advised to overclock your CPU straight away to higher clock rates. You should increase your FSB by small amounts. It is best to test the system fully in a taxing application for an extended period of time to ensure the system is stable at that speed. This process is repeated until the system does not test fully stable. The performance boost after overclocking can be substantial but a lot of considerations should be taken before trying out the steps used for overclocking.It is important to know the risks involved, the steps that must be done to obtain the results and a clear understanding that results will very greatly.

As told before Graphics cards can also be overclocked.Overclocking the graphic cards is a much easy option as they are generally done with the help of software's such as NVIDIA's cool bits or Riva tuner. Graphics card generate enormous amount of heat and without any proper cooling overclocking of graphic cards should be avoided. Below overclocking of a graphics card is explained by taking ATI 9800 pro as the base.

In order to overclock ATI cards you must have Riva tuner which can be downloaded from here.

The first step in overclocking your graphics card is to click the button next to customize word which is low level system settings. Now a new screen pops up which shows the Core Clock and Memory Clock speeds.

Now you simply have to change the core clock speed and the memory clock speed little by little and keep testing them. Click on the checkbox at the top that is labeled "Enable low-level hardware overclocking".Also Make sure that the "Apply overclocking at Windows startup" box is TICKED.

So that was in brief about how to overclock a graphics card. Now we will have a look at the advantages and disadvantages of overclocking in general.

Advantages

1) Allows you to make your lower end CPU run at higher clock rates which reduces the need of buying a high end CPU.

2) Performance in games, encoding video applications increases drastically.

3) Benchmarks of your CPU and GFX card increase significantly. It makes sure that full juice is taken out of the CPU and GFX.

Disadvantages

1) The lifespan of the processor decreases. It is said that if you overclock your processor to a great extent then it lives 8-9 months less than its lifespan.

2) Considerable amount of heat is generated and without any proper cooling this can be dangerous. Several cases have been recorded where the Processor or GFX card has burnt out.

3) High performance fans and high quality cooling systems provide great amount of noise. The noise is pretty loud to disturb someone listening to a song at low volume.

4)Overclocking will result in the termination of the warranty of the product. So if anytime any problem arises it will be difficult for you to get the product replaced or repaired.