Sorry for top posting, but if you didn't cut and paste that Jim you
certainly should post it to a website. Great explaination.

Jim wrote:
Ok, one problem here is that the marketing hype leads the advertising people
to not quite state things correctly. Let's forget the details of that ad,
and talk as accurately as possible.

The CPU FSB is more correctly stated as 200MHz (actual), but since it
employs DDR technology, it's *effective* rate is 400MHz. The "400MHz"
number you see in the ad is actually misleading, the CPU FSB does NOT
physically *run* at 400MHz, it runs at 200MHz (that's what would show up on
a scope!), *but*, because the DDR technology it employs allows data to
travel BOTH on the up and down side of each cycle (per MHz), it's *behaving*
as if it data was traveling on ONE side of the cycle, but at 400MHz! Get
it? It's a marketing gimic, the CPU isn't actually *faster*, it's more
*efficient* (2x in fact) at the same speed of a 200MHz processor (1x) that
does NOT employ DDR technology. But the marketing guys don't like that sort
of explanation, they'd rather claim the CPU is a 400MHz processor! Looks
better in the advertising than "this is a 200Mhz processor that's more
efficient and acts like a 400MHz processor". Not nearly as appealing,
right?

Same thing w/ Intel, they say their top-end processor is an 800Mhz CPU.
Technically, WRONG! It's a 200MHz processor that uses DDR technology (2x)
*and* twice as wide a data path (2 x 8 bit), making for an *effective* rate
of 200MHz x 4 = 800MHz. Whalla, the marketing guys are happy again.

Now to the memory. DDR400 (or PC3200) memory is marketed in exactly the
same fashion. It's 200MHz memory, but due to DDR technology, its
*effective* speed is 400MHz. But just as w/ the CPU FSB, it's really only
running at 200MHz (on the scope). Again, it's marketing hype. If we want
to be absolutely precise, that DDR400 (PC3200) memory is 200MHz x 2 (effect
of DDR) x 8 (bits wide) = PC3200. Some advertising people like the sound of
PC3200 instead of DDR400, so sometimes you see PC3200 referenced instead
(3200 sound more impressive than 400, I suppose). The PC3200 label also
implies it's effective bandwidth (3.2Gb/sec).

Bottomline, that AMD "400" CPU and DDR400 memory are, in fact, in PERFECT
sync, both are running 200MHz *actual*, on the "scope". What makes them
different/better is they are more efficient at that 200MHz speed than other
200MHz components that do NOT employ technologies like DDR.

Everything got all complicated in this area once DDR technology came into
the scene. Unfortunately, you can't take the advertising statements too
literally anymore. AMD did the same thing w/ their processors. Is an AMD
Athlon 2600+ actually running at 2.6GHz? No way, that's the hype, it's
actually 2.08GHz "on scope", AMD is merely claiming 2600 (2.6GHz) is the
*effective* performance compared to a 2.6GHz Intel CPU. Fact or fiction?
You decide.

HTH

Jim




"esara" wrote in message
om...

Accroding to this diagaram
http://www.viatech.com/en/k7-series/kt600.jsp

If for example My computer has DDR 400 and the CPU FSB is 400. In this
case I am wasting my memory speed. I mean the memory can send/receive
data to/from the chipset at speed 800Mhz(400*2) but the CPU which
suppose to handle these data can only work at FSB =400Mhz (I know the
internal speed is more than 400Mhz) but what I want to say is that
while the memory can supply data to the CPU at speed 800 the FSB of
the CPU can only take data at speed 400Mhz (so the FSB will slow down
the traffic). In this case this is not good design, the better is to
have CPU with FSB 800 or Why I bother to install memory DDR400, while
DDR200 will give the same performance provided that the CPU is FSB400.

Am I right?? any help would be very much apprciate it. Thanks.


Thanks





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