Changing a Multiplying Ratio and Voltage. Part II

The processors supplied from 2,8V have the least possibilities to change voltages. Unfortunately, among these processors are also processors of Pentium II 233/266/300. The processors that require 2V have the best possibilities to change voltages – Pentium II 333/350/400/450 and Celeron 266/300/300A/333. Their voltages can be changed from 1,8 to 2,6V by isolation of appropriate outputs.

The outputs A121, A120, A119 are on the front, and B120 and B119 – are on the back side of a slot. In total, there are 121 outputs on each side and the first and the last ones are marked as A1 and A121 (B1 and B121). And all odd-numbered outputs (A1, A3, A5, … A121) are on the bottom row and all even-numbered outputs (A2, A4, A6, … A120) are on the top row. To isolate an output, you have only to cover it with lacquer or to stick its wide part.

There are more exotic ways of the hardware overclocking. For example, you may make technological holes in the appropriate places of your processor and add special devices on its diagnostic connector. These devices allow changing the bus frequency and the processor voltage using some switches.

Changing a Multiplying Ratio and Voltage. Part I

Unfortunately, there is not any safe method enabling to change a multiplying ratio of the bus frequency by the hardware at home.

Similar to changes of the bus frequency, you can try to bypass the limit on the voltage supplied to a processor. To do this, you should isolate some processor’s outputs.

A processor informs a motherboard about its power of five voltage outputs VID (Voltage ID): from VID0 to VID4 (outputs B120, A120, A119, B119 and A121 accordingly). The combination of these contacts forms a binary number specifying the voltage that should be supplied on a processor. Each output may be either in the state of logical low or logical high. Thus, the entire voltage spectrum is described – from 1,3 to 3,5 V.


Logical Combinations Pointing the Voltage Supplied on a Processor











Voltage, V

0 1 1 1 1 1.30
0 1 1 1 0 1.35
0 1 1 0 1 1.40
0 1 1 0 0 1.45
0 1 0 1 1 1.50
0 1 0 1 0 1.55
0 1 0 0 1 1.60
0 1 0 0 0 1.65
0 0 1 1 1 1.70
0 0 1 1 0 1.75
0 0 1 0 1 1.80
0 0 1 0 0 1.85
0 0 0 1 1 1.90
0 0 0 1 0 1.95
0 0 0 0 1 2.00
0 0 0 0 0 2.05
1 1 1 1 0 2.10
1 1 1 0 1 2.20
1 1 1 0 0 2.30
1 1 0 1 1 2.40
1 1 0 1 0 2.50
1 1 0 0 1 2.60
1 1 0 0 0 2.70
1 0 1 1 1 2.80
1 0 1 1 0 2.90
1 0 1 0 1 3.00
1 0 1 0 0 3.10
1 0 0 1 1 3.20
1 0 0 1 0 3.30
1 0 0 0 1 3.40
1 0 0 0 0 3.50

Changing the Bus Frequency

Some motherboards, for example by Intel, have no opportunity to control the bus frequency and multiplier either at the software level and it is locked at the hardware level. But this situation is not fatal for overclocking.

To get “manual” access to the system bus, use the isolation of one of processor outputs which is responsible for installation of the bus frequency. If to cover this output with lacquer or to isolate it with a scotch tape, the bus frequency can be changed using either the software tools or some switches on a motherboard.

In Celeron and Pentium II/III processors an output B21 is responsible for auto installation of the bus frequency.

Turn Celeron on the side with no processor kernel on it, and Pentium II/III – on the side with holographic sticker on it. There is marking from B1 to B121 from each end of the contact track – a short strip of contacts is on the left while a long one is on the right. Find the 11th output on the long strip of contacts in the bottom row. This would be a contact B21 that should be isolated.

The Hardware Opportunities for Expedited Operation of Your Processor

The hardware opportunities for overclocking of your processor is closely related to the producer of your motherboard, the time of its production, the type of your processor, the limited warranty for your computer, as you must have direct access to all innards of your computer.

The easiest way to identify if your motherboard is suitable for overclocking is to read its manual. As a rule, if your motherboard supports overclocking, there is always a section in a manual, for example “CPU Speed Setup”, where you can find how and where all switches should be set to reach the required bus frequency or multiplier value. In the manuals for old motherboards you can also meet the tables of overclocking for Intel, AMD and Cyrix processors.

Using the hardware for overclocking, you may use the same recommendations as for the software overclocking: the significant increase in the bus frequency may have a bad impact on other devices, and changes in multiplying ratio may lead to the computer failure. In case of unstable operation of your computer, change all switches back to their standard positions.

Changing Voltage

The third possibility to increase the processor frequency is to change voltage supplied to a processor. This procedure also enables to stabilize the processor operation after increasing the bus frequency. Using this way of overclocking, it is necessary to keep a close watch on changes in its temperatures during its normal and extreme loading. In general, it is not recommended to increase the voltage more than 10-15% of par.

Open a section “Frequency/Voltage Control” and select a parameter “CPU VCore” (VCore). Change the voltage value. As a rule, a step of voltage change is equal to 0,05V. Never exceed a standard power voltage of the processor kernel by more than 0,2V. Always remember that a processor is rather sophisticated device that should not be used as a heater. If the temperature has reached 70-75 C during the extreme loading of your processor, you should return to the previous values of voltage.

A parameter “CPU VCore” has a value Auto by default that conforms an optimal voltage. The voltage rise to 0,1V and stabilization of processor operation during increasing the bus frequency has a positive impact on the processor overclocking.

Changing the parameter, that is responsible for the voltage of processor kernel, may lead to reducing the useful lifetime of your processor. This is related to an effect of electron migration, the probability of which is growing with a rise in voltage. Gradually, this may lead to some errors and then – to irreparably damages of your processor’s micro structure.

Changing a Multiplying Ratio

A multiplier is already flashed inside processors: for example, if the frequency of your processor kernel is 650 MHz, this multiplier is equal to 6,5 for the standard bus frequency. Any attempt to modify a multiplier may lead to the processor failure. The only way out of this situation is to install default parameters for BIOS.

A set of producers have equipped their motherboards with a switch that can be called, for example, Configure. This switch gives an opportunity to control changes of bus frequency, multiplying ratio and the voltage supplied to a processor, memory modules and video card from BIOS. For example, a parameter “CPU Freq Select” has got two values: Hardware and Software. The first value indicates the usage of appropriate jumpers on a motherboard, and the second value indicates the possibility to change multiplier via the software using BIOS.

To change the multiplying ratio, open a section “Frequency/Voltage Control” and select a parameter “CPU Ratio” (CPU System Frequency Multiple, CPU Freq Ratio, Multiplier Factor). Select the required multiplier which may have the following values: 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5 and other; or 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 2:5, 2:7, 2:9, 2:11, 2:13, 2:15 and other.

Some parameters, for example Processor Speed, have got a set of values that directly indicate the processor frequency: 233, 266, 300 and other. But, in fact, this parameter changes the multiplying ratio at a constant bus frequency that is equal, for example, to 66 MHz.

Changing the Bus Frequency

Modern motherboards support rather wide frequency ranges of FSB (Front Side Bus) – for example, from 100 to 400 MHz. It is unlikely to use the whole frequency range: first of all, a processor will be strongly heated and all positive effects of overclocking will be reversed, and secondly, some failures will occur in the rest equipment, for example, in video system. But it is possible to increase the bus frequency up to 10-20% without any implications.

Open a section “Frequency/Voltage Control” and select a parameter “CPU USB Clock” (CPU Host Clock Select, CPU Bus Frequency, CPU Host Clock). Select one of proposed values for this parameter. These values could be shown as a continuous spectrum, for example from 100 to 220 MHz, or a set of discrete values (in MHz): 66, 75, 83, 100, 103, 112, 124, 133 and other. To increase the frequency, it is recommended to select the value following the current one.

Most setup parameters of bus frequency have the value Auto or Default which is set by default and is the recommended one.

A parameter “CPU Operating Speed” enables either to install the user value of a bus frequency (a value “User Define”) or to select one of fixed ratios of CPU kernel frequency and a bus frequency.

Processor. Part II

The current processor frequency is set in a parameter “CPU Speed” (CPU Frequency (MHz), Processor Speed). As a rule, this is only an informational parameter that is a result of multiplication of other two parameters. For example, a value “200 MHz” indicates a result from the multiplication of the bus frequency “66 MHz” and multiplier 3. But sometimes this parameter allows monitoring the configuration of the rest parameters in this section. For example, it can be set to Auto or Manual. In the first case, all appropriate parameters have default values while in the second case you have an opportunity to set all necessary values yourself. Of course, to carry out overclocking, you have to use manual control of parameters.

AMD, having produces a line of processors Atlon XP, caused a confusion with the correct marking. For example, a processor, marked as Atlon XP 2100, actually have a frequency of 1,67 GHz (133 Mhz*12,5).

Thanks to various modern technologies, a processor with a nominal frequency of 1,67 GHz shows the results which correspond to the processors by Intel with a frequency of 2,1 GHz. But it is more likely a marketing strategy. In office applications, AMD processors show the results that are equal to the results of the appropriate processors by Intel. From the other side, AMD Company produces processors with unlocked multiplier. So, it is possible to overclock your old processor, for example AMD K5 (or Atlon XP 1700), on the basis of the appropriate capabilities of your motherboard.

Processor. Part I

A processor is a commercial product. That’s why no one computer company produces only one kind of processors. They produce the so-called product line of processors. It is always built using the same technology and the same materials. The difference is set for ready product: “fast” processors are expensive and “slow” processors are cheap. This difference arises from the multiplying ratio of a bus frequency which formally cannot be changed. In some cases you may try to change it yourself. But if it cannot be changed, you can try to change the bus frequency.

Thus, if you have a processor of middle frequency and price, it can be easily overclocked to the speed of more expensive and “fast” models. The outdated models of processors can only be overclocked to 10-15%.

You can overclock your processor using BIOS or switches on your motherboard.

How to Increase Computer’s Productivity Using BIOS?

The higher the bus frequency and the bus multiplying ratio (multiplier), the higher clock frequency you will get. It is better to increase frequency from a multiplier – this influences only processor and does not affect the other elements. But in most cases this procedure is unavailable.

In most modern versions of BIOS all setup parameters for multiplier, bus frequency and voltages are listed under the heading “Frequency/Voltage Control” (CPU Frequency Control, Hardware Monitor Setup). In older versions of BIOS some parameters for monitoring the bus frequency can be found in “BIOS Futures Setup”.

Computer Overclocking. Part II

The simplest way to overclock a processor is to change a value of a bus multiplying ratio (multiplier). This is also the safest way: the voltage on the processor’s kernel and the bus frequency are stable. The other elements – memory, video card, hard disk – are also unchangeable. But this way of overclocking can only be used for outdated processors and motherboards. All modern processors, with some exceptions, have unchangeable multiplying ratio.

The second way of overclocking is to change the bus frequency. As the processor’s frequency is defined as a multiplier multiplied by the bus frequency, this is often the only real way to increase the productivity of your processor and other elements connected by this bus. But this method may cause a set of negative effects: the screen may be off because the video card cannot operate normally with increased frequency; all data on the hard drive will be lost because of increased data flow; and, finally, memory modules will be failed. Nowadays, the bus frequency is also recorded in the processors by Intel, so if you change it using system tools, a computer stops functioning.

The third way of overclocking is to increase the voltage supplied to the device’s supply contacts. This is the most dangerous way that may “burn” all your devices.