FSB, DDR etc

[Hoolio]

I was wondering something.....
You have an FSB of 100Mhz
You have DDR200 ram
You have an AMD athlon(FSB200)

Now just a couple of questions:
Now in theory both the processor and memory are working at 200Mhz.

So I ask, why not then actually use an FSB of 200Mhz and forget about DDR and the DDR athlon core.

Therefore multipliers would make sense once again, (because 8x the Athlons DDR core bus should in theory be 1600) but instead it is 8X 100. (i know I know multiplier of 8 x the fsb).

I could understand the point of the DDR athlon cores when memory was not ddr, but now if both the core and the memory is ddr then the core and memory are running at an effective fsb of 200Mhz. So why not actually use an fsb of 200Mhz.

I may be missing a large point here, it may be because I have not read a hardware review somewhere along the line.

Please explain, and don't be patronising plz, I am not stupid and no need to be rude (i have had some rude replies to questions I have asked before).

(Also funny, AMD come out with DDR cores and intel have to go one better QDR).

 

[Scout]

I'm no Electrical Engineer... but I think the answer lies in the fact that running a bus at 200 MHz. is kinda hard. That would mean you have to design board traces and so forth that will allow a "clean" signal pulsed at 200 million times per second!

DDR means the bus transfers data on both the rising edge as well as the falling edge of the signal. And of course, the Pentium 4 bus transfers data four times... not sure how that works! The DDR trick increases the throughput of the bus without increaseing the actual frequency. Pretty neat trick!

Scout
700 Mflops in SETI!

 

[eden]

Yes indeed, which is why the P3 bus can barely itch over 150MHZ, due to its architecture making noise above them speeds. DDR eases all this simply by doubling the speed without tinkering actual frequency. Like clock speeds with multipliers, a P4 NW is actually 100MHZ. The multiplier can be Deca Data Rate, to make 1GHZ, but of course it is way higher than this, though I don't know numbering nomenclature like these ones!

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Intel and AMD sitting under a tree, P-R-O-C-E-S-S-I-N-G!