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Does the cpu clock speed and front side bus get generated by the crystal oscillator/clock generator? Or does it get generated on the cpu? If it gets generated by the oscillator, how does it know what clock speed of the cpu is?

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That depends a lot on which CPU is used.

On older computers (e.g. 68000, 80286) the oscillator is on the motherboard. You know what the CPU's speed is and you manually set jumpers to the CPU gets the right clock frequency.

On somewhat more modern computers (AMD K6-2 300, P1-166, ... era) this was the same but instead of jumpers you often got some control via the BIOS.

One recent CPU's the clock generation is largely build into the CPU itself. You can set a few pins from the BIOS, essentially asking the CPU 'please run at this multiplier' or 'please use these settings', but the control is on the CPU and if it is locked then that request will not be honoured.

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So in modern cpu, the crystal oscillator is built into the cpu? or is there another technology used? – agz Apr 23 '13 at 4:42
I am convinced that I read it somewhere that the clock generator was on-die since the Nehalems (That is the first generation i7's, with the memory controller on board and something called an uncore.). The best I can find today however is on wikipedia: "With Sandy Bridge Intel has tied the speed of every bus (USB, SATA, PCI, PCI-E, CPU cores, Uncore, memory etc.) to a single internal clock generator issuing the basic 100 MHz Base Clock (BClk)."". – Hennes Apr 23 '13 at 16:20

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