Is FSB the mobo Bus Clock?

[chzlchp]

If the answer to that is YES, than I've finally got it!

In front of me I have:

• description of my existing Dell (thankyou 'BelArc Advisor')
• tech data for my new mobo - ABIT NF7-S
• A really neat book called How Computers Work (Que Press, auth. Ron White)
• tech data for my new CPU - AMD Athlon 2600+ Barton
• some Googled glossary items that describe how processor speed divided by bus speed begets multiplier
• a cup of cold, hour-old coffee

The last key to this puzzle is this, and I just can't seem to find it succinctly defined for me:

>My mobo tech data says I can support 200/266/333/400MHz FSB processors.<

Is the above a description of my mobo clock speed[s]?

[JTH]

Nope. There is no such term when referring to a processor.

That spec refers to the FSB of the CPU that your motherboard can support. Double each figure to find the correlating compatible CPU. For example the Pentium 4 2.8C runs at an 800mhz FSB, therefore it would be designed for that board. You could of course run a P4 2.8 B (533mhz or 266 on your mobo), but you wouldn't be utilising the full potential of your motherboard. In your terms, the 2600+ Barton runs at 333mhz FSB.

Hope this has cleared some things up.

[WhatsThisBoxFor?]

JTH, you are right about doubling the speed, but we are dealing with the Athlon XP processors, and they go up to 400FSB, and so the numbers are already doubled (i.e. 200 - 400Mhz), with the P4's they are quad pumped, and so you times that by 4 (i.e. 200 - 800Mhz).

chzlchp, that motherboard will support that processor, since it you have full support for the Athlon XP speeds.

[chzlchp]

Well, yea, kinda...yes and no.

Here, then is the hard issue (question) that I was hoping a clarification would illuminate for me.

The owner's manual for my mobo (ABIT NF7-S) reminds me to, "...not forget to set the correct bus frequency and multiple for your processor."

I know the processor speed - it is 1.9GHz. That was readily available in the tech data for my (AMD Athlon) CPU. What I needed to discover was at least one of the other two elements of the formula (Processor speed/bus speed = multiplier). Now, I'm back at square one.

[WhatsThisBoxFor?]

It should automatically setup the multiple correctly, if not here is the page I use for identifying processor speeds etc: http://tech-report.com/cpu/ it should have the multiple. The bus speed is the fsb (front side bus).

[glc]

The 2600+ Barton runs at a CPU bus speed 333 and a motherboard bus speed (FSB) 166. The NF7-S supports AMD processors from 200 to 400 CPU bus (100 to 200 motherboard FSB).

A P4 2.8C runs at a CPU bus speed 800 and a motherboard bus speed (FSB) 200.

[gamer4life]

Originally Posted by WhatsThisBoxFor? with the P4's they are quad pumped, and so you times that by 4 (i.e. 200 - 800Mhz).

what exactly does pump mean and how is it done?

[WhatsThisBoxFor?]

I believe it means that data is passed 4 times in one clock cycle, a bit like with double data rate it is passed on the start and end of a clock cycle. Going into very gray area here/taking guesses: I imagine the mhz are the frequency, and this is like the frequency of radio waves etc, then it is that data is passed at the start, and the middle, bottom, and the end of the cycle, although I think this is probably wrong it is my best guess.

[gamer4life]

well i know data can't be "latched" at the middle of a clock cycle it is only available on the rising or falling edges.

[WhatsThisBoxFor?]

Well if it is a transverse wave does it rise and fall 4 times? Once at the start, then at the top of the first, then again at the top, then again at the middle, and the bottom of the wave. Or is my science/IT not very good.

[Cricket]

Take a look this illustration that shows where the data reads occur during a quad pumped clock cycle.

Cricket

[WhatsThisBoxFor?]

Thankyou Cricket, that made it a lot clearer for me.

[chzlchp]

WTBF, you slipped the whole answer in, kinda sneaky like: '...bus speed is the fsb...'

That is what I needed! And thanks a million for the link to the CPU tech stuff. On another level, it kinda galled me that I couldn't come up with the answer by research, 'cause I think that's sorta the whole point, and (sometimes...not gently) the advise given by forum participants.

Thanks again for all the help, folks.

[gamer4life]

Originally Posted by Cricket Take a look this illustration that shows where the data reads occur during a quad pumped clock cycle. Cricket

Maybe I'm going crazy, but isn't that a sine wave and not a square wave. Since when did computers stop using square waves for their clock signals?

[ric449]

I made the illustation. It was the first wave that came to hand, does it matter?

[gamer4life]

Originally Posted by ric449 I made the illustation. It was the first wave that came to hand, does it matter?

yes, it says one of the reads is at the top of the wave. I thought there has to be a state change for anything to happen. (i.e. going from 1 to 0 or 0 to 1, which is a rising or falling edge)

[chzlchp]

gamer4life...

Us Maryland folks seem to have a soft spot for the Stars & Stripes. Seems to be flapping a little harder than the Union Jack (that's an observation, not an opinion-mean no offense by it). Don't know about where you are, but up here in Harford County, it must have something to do with the strong [Hurricane Frances] tailwinds coming thru.

[ric449]

Well, heres where the inspiration came from:

http://www.directron.com/fsbguide.html#part3

Don't ask me how it does it, but all I know is that it signals 4 times in one cycle one way or another.

[Craig100]

Yes, Technically it is impossible to get a square wave like a digital pulse...in reality if u maginfied it, it is soo small a curve(wave) that it seems to be like a digital, square wave.

Craig