FSB question

[cronus1914]

Hey all! I have a Pentium 4 processor and I was wondering why software like Sandra tells me that my Front Side Bus speed is 100MHz but the data rate is 400MHz. I don't understand why these programs constantly make reference to the FSB being both 100MHz and 400MHz. What's the deal?

BiLL

[mjc]

Because the FSB is really 100MHz.

Back in the days of yore, BP (before Pentium) the original bus speeds where rather low, so Intel came up with a method of "doubling" the spped of the processor by "double pumping" the FSB as it got to the processor. Speeds overall increased and that idea was dropped, until recently, they brought back the concept, refined it a little and lo, a processor that essentially has a 400MHz bus speed on a 100MHz FSB.

[Active Techster]

Hey MJC.

At what speed did this get reintroduced?.....

Out of interest is this why some old cases have an LED display on the front that allow you to increase the FSB with a button on the front?

[mjc]

Yes, that is the turbo button.

The 200MHz (fsb) AMD chips essentially brought back doubling. P4s brought quad "pumping".