# CPU Multiplier

#### tomvangelder

##### Distinguished
Hey all,

I've got a queston about the CPU multiplier.

I've been reading alot about it since im overclocking my pc for a practical project. I know what it's role is concerning overclocking.
But I was wonder how this multiplier exactly works.

I always compare the FSB with a funnel.
If you got a certain flow, which is stronger then the funnel can digest, the flow wil save up.
The same happens with the FSB. If the FSB isnt high enough, the cycles per second can't get through the FSB and will save up. that is the wait time you have while working on your computer.(ofcourse more things will influence this)
But when the cycles get through the FSB they reach the Multiplier. But how does this multiplier work?
The FSB is the limit you have(same as the funnel) so you have to raise the FSB to create more speed.
But since you can multiply the FSB with for example 20. you get a higher CPU frequenty. Anyone got a clue how this multiplier works?

Hopefully I made clear what I meant since my english ain't on a sufficient level as I wanted it.

Thanks for your responds

Tom v gelder

The netherlands

#### 4745454b

##### Titan
Moderator
I'll take a stab at this but I'm not sure I'll be able to do it justice.

Eons ago (in computer terms of course.) the CPU and the FSB moved at the same frequency. Everything was matched, life was good. We then hit a problem. We couldn't (at the time) move data through the FSB to keep up with faster CPU clock frequencies. We could either not increase CPU frequencies or unlink them from the FSB. Because transferring data to and from the northbridge is only a part of what the CPU does, its a good thing that we allow it to run faster then the FSB can keep up with. If we didn't our fastest CPUs would be 1333MHz.

As far as I know, the actually frequency is set by a clock generator much the same way the FSB is set. It actually gets its input frequency from the FSB, and multiplies it by whatever value is set by the multiplier.

#### tomvangelder

##### Distinguished
Thanks for your relpy

so basicly the sort of sinus you have from the FSB gets multiplied?
since the frequenty is a sinus movement. (every max and min is a click)
for example you have a normal sinus with a period of 2 pi
and then it gets multiplied for example by 10. you get a sinus period of 0.2 pi.
which goes much faster.

hopefully some people could confirm this

Greetings

Tom