Buss speed?

It really depends on the CPU for what you mean by bus speed.

For older Intel CPUs such as a Core 2 Duo or Core 2 Quad, then no. For example:

A Q6600 has a FSB of 1066MHz. Its QDR (Quad Data Rate) which means that it runs at 4x the mobos FSB speed of 266MHz.

A Q9550 has a FSB of 133MHz which is 4x the mobos FSB speed of 333MHz.

The FSB of 266MHz/333MHz also determines the CPU speed by taking that number and using the multiplier to get the CPU speed.

If its a AMD CPU or a newer Intel Core i3/5/7 then the CPU runs on a different system and normally the CPU has whats called a BCLK (Base Clock) which determines the CPU speed by using the multiplier. But it has a IMC (Integrated Memory Controller) that runs at its own speed using either HTT (HyperTransport which is for AMD) or QPI (Quick Path Interface which is Intel) to communicate with other cores, memory and system parts.

I suspect the OP wanted to know if when buying a motherboard if the rated bus speed of the board has to be the same as the CPU, I could be wrong....

If you are talking about Core 2's (LGA775) then you require that the motherboards rated FSB speed be the same or higher then the CPUs. Although a CPU with a higher FSB then the motherboard will still work, however its speed will not be what it is rated at. Example:

266MHz FSB CPU with a 10x multiplier in a 200MHz FSB motherboard. Instead of 266x10=2.66GHz the CPU would run at 200x10=2.0GHz.

Hope that was what you wanted to know.