2630qm, 2720qm and bus core ratio

ok hardware gurus, sorry for the elementary question -- have i got this right or am i mixed up --

the i7 2630qm runs at 2ghz and its bus/core ratio is 20. the i7 2720qm runs at 2.2ghz and its bus/core ratio is 22.

are these external clock speeds -- meaning that the 2720 runs internally at 48.4 ghz (2.2 * 22) and the 2630 at 40? in other words, a 21% difference? similarly, the 2720 would turbo internally to 72.6 ghz (3.3 * 22), 25% higher than the 2630 would, at 58ghz?

 

No, the bus speed / baseclock is 100 MHz, the CPU speed gets determined by baseclock * multiplier. Thus a multi of 20 results in a CPU speed of 2.0 GHz.

The maximum turbo multiplier of the 2630QM is 29 which results in a max CPU speed of 2.9GHz, the maximum multi of the 2720QM is 33, which results in a maximum Turbo Frequency of 3.3GHz. (These numbers are for only one core active)

Your CPU will slow down itself when there's no work to do (by lowering the multi) and speed up when there's a lot of load (raising the multi).

 

great; thanks! listed speeds are internal, and the core/bus ratio is just another way of expressing the internal clock speed

 

Yeah, that's right, the core/bus ration equals the cpu speed..

 

The base clock is a reference clock which all the important clocks (SATA, CPU, mem etc) are determined from.

The clock itself imparts no performance benefits (eg doubling the base clock and halving all the multipliers would perform the same).

With sandy bridge (2nd gen core i series) the base clock is generated internally in the CPU and has extra things hooked into it meaning it can't be changed very far without causing instability (104-107mhz).

It used to be generated on the motherboard meaning that motherboard makers could isolate the more sensitive items that you don't want to overclock and let you increase it.