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Old 4th July, 2004, 12:20 PM
Aedan Aedan is offline
Chief Systems Administrator
Join Date: September 2001
Location: Europe
Posts: 13,075

This is the way I understand things are:

HTT Bus: The HyperTransport link to the 'Southbridge' and it's peripherals, such as keyboard, mouse, PCI slots, AGP slots and anything else that's not memory!

Master clock: The master clock signal fed to the CPU by the motherboard. This also appears to be known as the HTT clock, which might be where a lot of confusion comes from.

Memory bus: The DDR memory bus between the CPU and the memory. This is directly connected to the CPU.

Core speed: The speed of the CPU core itself, as opposed to any I/O.

FSB: AMD64 doesn't have an FSB, as the memory controller is directly on the die itself.

From my understanding, the HTT clock is actually the master clock for all functions on the CPU. In other words, it feeds into the phase locked loop (PLL) on the CPU that then derives the various frequencies that the CPU needs.

The core frequency is generated by the PLL by multiplying the master clock frequency upwards.

The memory bus frequency is generated by the PLL by either multiplying or dividing the master clock frequency.

The HTT bus speed is set by taking the master clock and multiplying it up.
Any views, thoughts and opinions are entirely my own. They don't necessarily represent those of my employer (BlackBerry).
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