CPU and FSB

[Bozee89]

Recently I have been reading and researching about CPU and FSB I had some confusion that I want to clear up.

We all know that the chipset integrates every components in the motherboard specifically the Northbrodge used to manage the data flow between the CPU, main memory (RAM) and PCIe slots through what we call system bus. Now assuming that we have in the first PC with a CPU of 3.4 GHz speed and 100Mhz FSB and the second PC a CPU with 3.0 GHz CPU speed and a 200Mhz FSB. In this scenario the second PC will be faster regardless of higher speed of the first CPU that is because of the faster FSB supported by the motherboard in the second PC, is this scenario correct? I have more question coming up but first I need to clear up the basics.

 

[popatim]

Not correct. FSB is modern computers is just a reference clock but it does affect all the other clocks, most problematic when overclocking the fsb is pci & pcie.

 

[Bozee89]

Then what is FSB ecaxtly? How it works and how it affects other PC components? Doesn't it affect PC components when you overclok by reducing the multipliers?

 

[CountMike]

FSB (Front Side Bus), interface of CPU with rest of the system. With many controllers moved to CPU itself it's largely replaced by other interface based on MB. "CPU Host Clock Control" for instance. That times Multiplier = CPU frequency.
When you lower Multiplier you effectively downclock processor, not overclock it. When you change multiplier only CPU frequency is affected but changing FSB (or whatever it's called) other components like memory and chipset are affected.

 

[Bozee89]

FSB (Front Side Bus), interface of CPU with rest of the system. With many controllers moved to CPU itself it's largely replaced by other interface based on MB. "CPU Host Clock Control" for instance. That times Multiplier = CPU frequency.
When you lower Multiplier you effectively downclock processor, not overclock it. When you change multiplier only CPU frequency is affected but changing FSB (or whatever it's called) other components like memory and chipset are affected.

When you say FSB is an interface of CPU do you mean ONLY the CPU it seems to me it's a bus in the motherboard connected by 2 interfaces, the CPU and the northbridge.

 

[Bozee89]

I think i am confused i'll do some research then i'll come back to participate

 

[popatim]

FSB is a reference clock. your example above will be false because the cpu with the 200Mhz fsb will still be out performed by the 3.4ghz cpu; their ram will operate at the correct frequency as will their drives and pci/pcie buses. The reason for this is the 3.0ghz/200mhz fsb cpu will have a multiplier of 15 while the 3.4/100mhz fsb will have a 34 multiplier. thats the only difference with regards to performance as long as cpu cores are essentially the same. So a 3ghz cpu should be out performed by its 3.4ghz brother.

All the other devices would have the appropriate multiplier/divider applied to keep those buses in spec.