clock circuit of computer processors

[Neo017]

a chip with 2.5Ghz clock .does it actually work on 2.5 GHz pulses for every operation ?

 

[embedsys]

Yes. but it works inside the Chip. externally you will give only few MHz Clock to the chip. Every Chip will have PLL block inbuilt and it will distribute the clock to other functional blocks. Mostly 2.5GHz represents only the chip core the speed.

 

[Neo017]

so say for example the i7 which works at 2.5 Ghz is triggered by an external circuit for the clock ?

 

[embedsys]

Yes. not only i7, Every chipset should have clock source(typically few MHz) which makes the device/peripheral to work..

 

[betwixt]

You can't easily carry GHz signals on the PCB or through the processor socket so a lower speed is generated on the main board (typically around 200 - 300MHz) and it is multiplied up by a PLL and oscillator built on to the processors own silicon. On some processors there are "multiplier pins" which decide by how many times the motherboard clock is multiplied to give procesor clock, it's one of the ways 'overclockers' boosted system speeds. On most modern processors the manufacturer sets the multiplier internally and the only way to change speeds is to adjust the motherboard clock which can also have other consequences to peripheral devices whch also use it.

Brian.