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Which is it?

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May 29, 2001 4:38:24 AM

I've been searching here at THG as well as other sites, and I hear references to the Duron proc having a 100mhz fsb, and a 200mhz fsb. Which is correct? And why?

My brain has performed an illegal operation and will be shut down

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Anonymous
a b à CPUs
May 29, 2001 4:44:57 AM

the bus is

200 MHz

its 100 but its DDR and double pumped
giving it 200MHz effectively

--call it what you wish, with this machine I can make mercury flow in 3 directions at once--
May 29, 2001 4:54:49 AM

So does that mean I need to have DDR RAM for the fsb to be 200mhz?

My brain has performed an illegal operation and will be shut down
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May 29, 2001 4:59:02 AM

no, most socket A motherboards use PC133 and the 200mhz DDR.
if you buy a DDR motherboard, you'll need DDR SDRAM.

----------------------
Independant thought is good.
It won't hurt for long.
May 29, 2001 5:00:25 AM

Nope. The Duron FSB will still run at 200MHz even if you just have standard PC100 or PC133 RAM.

Kelledin

bash-2.04$ kill -9 1
init: Just what do you think you're doing, Dave?
May 29, 2001 5:17:08 AM

What do you mean by "it's 100 but it's DDR and double pumped"? I think if I understand that, then maybe I'll finally have a grasp on this!
BTW- thanks everyone for the info! Like I wrote before, I tried searching here & other sites but all the info I could find assumed that the reader understands the basic premise, and I don't!

My brain has performed an illegal operation and will be shut down
May 29, 2001 5:19:15 AM

Oh yeah, sorry if this is a dumbass kind of question...

My brain has performed an illegal operation and will be shut down
May 29, 2001 5:44:55 AM

It's a little bit technical...you see, the frequency (MHz) is a measure of how often some little clock crystal pulses ("ticks") in your system. Traditionally, logic circuits have been able to move data only once on each tick of that clock crystal.

The rules changed with DDR. Now circuits are able to send data once every tick of the clock crystal, and also once half-way between one tick and the next. Even though the clock is still ticking at the same frequency, twice as much data is getting moved for every clock tick. It's generally the same effect as having a clock crystal ticking at twice the frequency.

Kelledin

bash-2.04$ kill -9 1
init: Just what do you think you're doing, Dave?
Anonymous
a b à CPUs
May 29, 2001 5:55:28 AM

think of one clock cycle as going - from off to on and back off.
that is happening 100 million times a second on a 100 MHz bus

the way to look at it is
SDR - one bit of information is sent every time the cycle goes high (on)
DDR - one bit on the Rising edge and then another on the Falling edge.
QDR - one bit on the transistion from off to on, one bit when it is on, one bit on the transition from on to off, and the fourth bit when it reaches off.


So, DDR simply sends two bits of info in the space of one.
I think ??? that RAMBUS is Quad pumped (Raystone would know!)

however, we all start at the end and finish at the begining
May 29, 2001 6:22:49 AM

Actually, I understand that part (SDRAM vs. DDR RAM). What I'm getting at is does the CPU itself send data on the rising and falling edge of the clock cycle? And when I'm setting up my mobo (Asus A7A266) do I indicate the fsb as 100mhz or 200mhz, assuming no oc'ing?

My brain has performed an illegal operation and will be shut down
May 29, 2001 6:27:10 AM

Yes, the CPU sends on both edges of the clock cycle. I can't speak for the A7A266, but every Athlon mobo I've seen has you specify the fsb speed as its base clock (100MHz or 133MHz) rather than its "effective" clock.

Kelledin

bash-2.04$ kill -9 1
init: Just what do you think you're doing, Dave?
May 29, 2001 6:41:35 AM

Thanks a million dude!!! I finally understand! That's what I love about this forum: people in the know helping those of us who aren't (but are learning).
BTW- tomorrow I rip my system apart (celery 633 w/ an integrated PCChips mobo, don't you feel sorry for me!) to replace it with an AMD system. Low end for now, just to get it running, but I really start drooling when I think of the upgrades that I'll be able to do in the future! Couldn't do that with my PCChips POS!!!

My brain has performed an illegal operation and will be shut down
!