There is no "common" frequency. As new technology develops, the speed of the front side bus and newer system buses continuously increases.
front side Bus...(FSB) or System Bus
The root frequencies of an Intel motherboard include the support system frequency bus. This includes the processor and the CPU Voltage and VRM Frequency.
Bus Frequency- (Also Known as Bus Speed) is the rate (or frequency) at which the data on the motherboard is written and read. :)
The faster the CPU can push data around the motherboard is mesured as a frequency
processor frequency
processor frequency
Front Bus and 1600
The frequency of a system bus is measured in Hz. Modern computer system buses operate at hundreds of MHz or at GHz.
Host Adapter
The SM Bus Controller, or System Management Bus, is installed on the motherboard. It was developed by Intel. It varies on the specific place according to the motherboard.
A system bus frequency is 1600 MHz. A CPU frequency is 166 MHz to almost 4GHz.
data bus, system bus and host bus.