Multi-core CPU clock speeds

[7031]

I had never questioned this until now, but my friend claims that with a say, 3.2Ghz quad core CPU, that it is divided to 800Mhz per core. He's a pretty intelligent guy so I'm sure he knows what he's talking about, but I had always assumed that this would mean 4 cores, each at 3.2Ghz? Yes, I'm sure that the CPU is throttled to save power, but I would have assumed that each core at least is capable of running at 3.2Ghz.

I know this isn't exactly technical support, but can anyone give me a valid answer on this?

Edit: Looks like he's posted the same question on FacePunch: http://www.facepunch.com/showthread.php?t=957847

[Aloone_Jonez]

It's not true, a 3.2GHz quad-core processor is 4 cores running at 3.2GHz

The reason why processors with more than once core appeared is because increasing the frequency beyond about 3.2GHz became impractical for various reasons. CPU clock speed is what it says, he's probably confusing it with the bus speed which will be 800MHz.

[7031]

Yes, that was what I had assumed. And yeah, that's what I had heard myself, even though Intel claimed to have Pentiums at like, 4Ghz.

Yeah, I had assumed he meant the bus speed at first.

[Aloone_Jonez]

Yes, I believe 4GHz has been done before but it's more efficient to have more cores and clock at a lower frequency.

The bus speed also has nothing to do with the number of cores, the motherboard generates the clock for the bus and the CPU multiplies it up.

[Lead Head]

Yup, the cores all run at the rated clock speed. The fastest (GHz wise that is) CPU released was the 3.8GHz Pentium 4, but it became unpractical to go beyond that clock speed so they began adding cores instead.


Whats interesting though is that earlier dual (and quad core CPUs) when they throttled down the clock speed during lose useage periods they would throttle down all the cores together.  The latest CPUs can actually throttle down cores individually, or even completely turn some cores off if they are not needed.