Using Both Methods

Using Both Methods

To achieve high performance, it is recommended that you combine both methods: increasing the processor bus frequency and changing the multiplier value. To set and evaluate different values of the processor bus frequency and its frequency multiplier, you must choose the optimal combination of these values, corresponding to the maximum performance.

For example, the results of overclocking Duron using both methods are presented in Table 8.6 and Fig. 8.17.

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Figure 8.17: Overclocking Duron using both methods
Table 8.6: Overclocking Duron by Combining Methods

CPU frequency (MHz) = FSB frequency × multiplier

CPUmark 99 rating

600 = 100 × 6


690 = 115 × 6


900 = 100 × 9


896 = 112 × 8


In the example provided in Table 8.6 and Fig. 8.17, maximum performance is achieved using a bus frequency of 112 MHz and multiplier of 8x (112 MHz × 8 = = 896 MHz), even though the maximum operating frequency of the processor corresponds to an FSB frequency of 100 MHz and a multiplier of 9x (100 MHz × 9 = 900 MHz). The difference in performance, according to the CPUmark 99 test, is approximately 5%.

Higher performance usually corresponds to combinations with high FSB frequencies, on which the frequencies of other buses are dependent. By increasing the FSB frequency, you increase the throughput of this bus and other buses of the computer system, as well as the performance of the processor and other subsystems. These include the video adapter, the hard disk, PCI devices, and RAM modules.

However, the increase of the clock frequencies and subsystem performance is limited not only by the capabilities of the components and technologies that they implement, but also by the chipset architecture and motherboard design. Furthermore, when approaching the limit, the computer system becomes unstable.

As a result of these limitations, it is often impossible to fully implement the potential of the CPU when overclocking it exclusively by increasing the FSB frequency. Because of this, it is recommended that you use the combined approach, increasing the FSB frequency and changing the processor multiplier.

Thus, simultaneous usage of both overclocking methods allows you to increase overall system performance and ensure the required level of stability.

To conclude this section, it is expedient to mention once again that changing the processor multiplier is only possible in combination with specialized motherboards that support this function. Examples of processor overclocking will be considered and analyzed in the next few sections.