Understanding External/Internal Frequency, Multiplier: What does all of this mean???
In the past, the motherboard bus speed had to match the speed of the CPU. As technology improved, CPU manufacturers kept making faster and faster CPU's. Motherboard manufacturers, such as Iwill, tried to keep up as best as they could by making a motherboard with a faster bus speed. However, when designing a new motherboard, motherboard manufacturers had to consider not only CPU frequency, but the chipset, memory, BIOS, etc. The reality was: No matter how hard they tried, motherboard manufacturers were always one step behind CPU manufacturers in designing bus speeds equal to CPU speeds.
The solution was to design a motherboard with a bus speed that can accommodate a faster CPU. To do this, the motherboard had to maximize the bus speed. For example, the current standard for motherboard speed is 100 Mhz. The CPU must match this same 100Mhz speed when loading data from memory, storing data to memory, and generally communicating with the motherboard. This is the CPU's "system bus frequency" or external frequency.
However, the CPU could still continue to work inside, i.e. process numbers/ equations internally, and do this during the same time it sends data out externally. This internal action in the CPU can be twice, three, four, or up to eight times the speed of the motherboard bus. This is the CPU's internal frequency. Think of your CPU this way: a 200 Mhz CPU actually means the internal frequency runs at 200 Mhz. As of now, no motherboard manufacturer makes a motherboard that has an external frequency that runs at 200 Mhz (but keep an eye out for Iwill!).
To understand the term multiplier, a 200 Mhz CPU can be set at 100 Mhz CPU (system bus frequency) x 2 (multiplier) if your motherboard runs at 100 Mhz system bus speed. Or, it may be set at 66 Mhz CPU x 3, if your motherboard runs at 66 Mhz system bus speed.
Before you adjust the CPU frequency or "overclock," you must first know your motherboard's bus speed. Iwill has several motherboards designed with both 66 Mhz and 100 Mhz frequencies. When adjusting frequency, select the frequency that matches your motherboard's bus speed in order to maximize your motherboard's performance.