FSB - what is it

[skimzzz]

Since you can OC virtually any CPU by raising the FSB, what is the difference between a 100 and 133 rated FSB CPU? If a CPU is rated at 1330 mHz, what would be the diff if you ran it at 100 x 13 versus 133 x 10?

thx

 

[FUGGER]

On most CPU's the multiplier is locked, so the only way for OC is to raise the FSB.

In your example, the 133x10 config would be slightly faster.

Proving once again that <A HREF="http://www.zombo.com" target="_new">anything is possible</A>.

 

[ath0mps0]

The FSB (Front-side-bus) is the communications path between the CPU, chipset and memory. It is also a primary determining factor in PCI and AGP speeds. This means that any communications with the CPU are limited to the maximum bandwidth of the FSB. The higher the FSB, the faster these coms occur. Hard-core overclockers have found that increasing the FSB is more important, in many cases, than total clock.

In your example, 10 X 133FSB vs. 13 X 100FSB, not only is the FSB 33% faster with the former, the total clock is faster (1333MHz vs. 1300MHz). This will result in a much faster 3-5%? system.

I thought a thought, but the thought I thought wasn't the thought I thought I had thought.

 

[camieabz]

The other difference is that at 100MHz * 13 your mobo, memory, chipset, AGP and PCI are all running at 100MHz or at a speed derived from this number against a divider.

At 133MHz the mobo, chipset and memory increase their speeds and the AGP and PCI dividers either change or their buses speed up too (which can cause instabilities if they're too high and lack proper voltage attention).

😎 <b><font color=blue>The Cisco Kid</font color=blue></b> 😎

 

[ath0mps0]

yeah, that's why I recommend lowering the multiplier first (if possible), pushing the FSB to its stable limit (adjusting the PCI/AGP dividers as necessary), and then increasing the multiplier to the CPU's limit.

I thought a thought, but the thought I thought wasn't the thought I thought I had thought.