What actually determines the CPU speed?

[AgaBoogaBoo]

I've heard that inside of the cpu is a really small jewel or something like it which has something to do with it. I know how FSB, clock speed, clock multipliers, affect it, but is there such a thing as something within the cpu?

 

[KF]

I'm not sure what you are asking.

Externally there is an oscillator that generates a frequency which is the FSB. Call the frequency A. The CPU has an oscillator circuit which can be electronically adjusted. A logic circuit divides the frequency of the oscillator by the multiplier (like 13x). Call that B. A circuit adjusts the frequency of the CPU oscillator until B matches (locks to) A. The name of this arrangement is a PLL or Phase Locked Loop.

The external oscillator will usually use a crystal of quartz to set its frequency. Maybe that crystal is what somebody is calling a jewel. Probably what they will do is have another PLL that locks the external FSB frequency to the frequency at which the crystal naturally vibrates. They use crystals because the natural frequency of vibration is very exact and very stable.

 

[ChampionAtTufshop]

clock generator crystal is waht you are referring to i think

i think before you had to replace them to change the freq and whatnot

 

[lenjack]

multiplier X fsb = cpu clockspeed

 

[AgaBoogaBoo]

Originally posted by: ChampionAtTufshop
clock generator crystal is waht you are referring to i think

i think before you had to replace them to change the freq and whatnot

Today, do they differ a lot between cpus of same core just different stock speeds?

 

[ChampionAtTufshop]

Originally posted by: AgaBooga

Originally posted by: ChampionAtTufshop
clock generator crystal is waht you are referring to i think

i think before you had to replace them to change the freq and whatnot

Today, do they differ a lot between cpus of same core just different stock speeds?

yeah
although im not exactly sure, i think the clock gen crystal was to adjust the freq....now its done throu oscillator (that is so spelled wrong, but whatever lol)

its the exact same core for the most part....unles its a new process (ie, palomino and thoroughbred) in which they just adjust the clock multiplier to change the overall speed