SetFSB is a popular program that allows you to change the SBus frequency. This frequency is set by the motherboard and is called FSB. Since this frequency affects the CPU frequency, you can overclock the CPU by changing it upwards. SetFSB supports most motherboards, which is a big plus. Start the program and if your motherboard is supported, select the FSB frequency and press "Set FSB". Then test the system on this frequency.