FSB confusion

[MisterChief]

I'm a little confused as to why processor manufacturers label their products with 400, 533, 800+ FSB speeds when in reality they only run at a fraction of the advertised speed? For example, a Celeron D has a FSB of 533mhz, but runs at the stock speed of only 133mhz in the BIOS. I don't get it.

Edit: I remember someone telling me about multiplying the bios speed by 4 (200 times 4= 800). What does the 4 stand for?

 

[mwmorph]

the 4 or 5 or whatever is the fsb multiplier. it is the advertised speed it runs at.. it works like ddr ram. though ddr400 runs at 200mhz, that rates it at 400mhz.

 

[bmillerd]

It's all advertising. They sell it like that because a higher number is better to people that don't understand.

 

[ts3433]

P4s have a quad data rate bus (I think this is done by having two simultaneous clock signals--one reaching the rising edge as the other reaches its falling edge--and doing DDR transfer on both), thus an effective 400, 533, or 800 FSB speed.