Different FSB's

[Guest]

Hi, I was just wondering why the original computers up until a few years ago always had "true" FSBs of 66,100,133 etc.

Why does intel now have a "quad-pumped" 100mhz FSB instead of a real 400 mhz fsb? and same with the athlon/duron, or more specifically DDR, why not just make 266mhz RAM rather than 133x2.

Even if i do get an answer, what would be the difference between a 400mhz FSB and a quad pumped 100mhz?

Thanks

 

[FatBurger]

To answer your question, it's easier to make a double- or quad-pumped bus, than a true bus speed.
I'd say more, but I'll point you to <A HREF="http://forumz.tomshardware.com/modules.php?name=Forums&file=faq&notfound=1&code=1" target="_new">this</A> thread instead.

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[jollygrinch]

i'm not certain about this but i don't think there would be a difference between, for example, a 100x2mhz fsb and a true 200. the double pumping just enables information to be sent twice a clock cycle (4 times on the 100x4), if the true 200 mhz bus only sent once a clock cycle i wouldn't think there would be a difference in data rate/qality/whatever.

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[girish]

actually the real 200 MHz performance would be slightly slower since there is a "setup time" and memory latency involved with each transaction. a DDR capable memory will trigger setup at the first clock edge and continue with the next edge.

but then, why dont DDR at 200 MHz itself? we dont have that fast DRAMS!


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