fsb speed - why does it matter?

it seems to me that nobody needs a high fsb. since they could just
push the multiplier really high.

I can see the greatness of ddr since the same speed processor can
read/write twice as much per cycle. (i assume that the cpu has to be
ddr to receive or write double)

it seems to me that nobody needs a high fsb. since they could just
push the multiplier really high.



you cant push the multiplier high because its locked on most modern CPU's

also higher FSB = higher bandwidth = higher performance.

--
From Adam Webb, Overlag
www.tacticalgamer.com
CS:SOURCE server now active
"James Hanley" wrote in message
m...


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"Adam Webb" wrote in message ...
it seems to me that nobody needs a high fsb. since they could just
push the multiplier really high.



you cant push the multiplier high because its locked on most modern CPU's

nobody on an overclocking forum should be saying
"oh no, the multiplier is locked, what am I going to do"
Just like no technician is going to say, oh no, the file is 'hidden'
what am I going to do

also higher FSB = higher bandwidth = higher performance.

yeah, if it's greater width. i'm talking about speed only though.

James Hanley wrote:
"Adam Webb" wrote in message
...
it seems to me that nobody needs a high fsb. since they could just
push the multiplier really high.

you cant push the multiplier high because its locked on most modern
CPU's

nobody on an overclocking forum should be saying
"oh no, the multiplier is locked, what am I going to do"
Just like no technician is going to say, oh no, the file is 'hidden'
what am I going to do.

Better analogy: the technician saying "oh no, someone has wiped the disk
then turned it into slag in a blast furnace, what am I going to do?". Given
that people have spent close to 6 years trying to unlock Intel CPUs (no
success) and about 1 year trying to unlock locked AMD chips (no success), I
doubt there's going to be much progress on either front. The general view is
that both companies are using fuses inside the die, which can't be altered
once set.

also higher FSB = higher bandwidth = higher performance.

yeah, if it's greater width. i'm talking about speed only though.

Umm, say what? It's obvious that more throughput = more performance, and
throughput = bus width * bus speed, so increasing the bus speed (FSB)
obviously increases performance. Or do you think a Athlon running sync with
PC66 RAM (66MHz FSB, SDR, 64 bits wide) would perform just as well as the
identical CPU running sync with PC3200 RAM (200MHz FSB, DDR, 64 bits wide)?

--
Michael Brown
www.emboss.co.nz : OOS/RSI software and more
Add michael@ to emboss.co.nz - My inbox is always open

"Michael Brown" wrote in message ...
James Hanley wrote:
"Adam Webb" wrote in message
...
it seems to me that nobody needs a high fsb. since they could just
push the multiplier really high.

you cant push the multiplier high because its locked on most modern
CPU's

nobody on an overclocking forum should be saying
"oh no, the multiplier is locked, what am I going to do"
Just like no technician is going to say, oh no, the file is 'hidden'
what am I going to do.

Better analogy: the technician saying "oh no, someone has wiped the disk
then turned it into slag in a blast furnace, what am I going to do?". Given
that people have spent close to 6 years trying to unlock Intel CPUs (no
success) and about 1 year trying to unlock locked AMD chips (no success),

6 years? - but there are loads of articles on unlocking AMD chips, i'm
sure I think I saw one for the AMD XP 1500+, that's less than 6 years
old isn't it?

The general view is
that both companies are using fuses inside the die, which can't be altered
once set.

*******s.
So how can anybody overclock? Just by upping the FSB to whatever the
mobo supports?
I suppose that a CPU will have a built in multiplier at a fixed value,
and will assume a certain FSB speed. So if the FSB is lower then it's
underclocked. If it's higher then it's overclocked. Or does it not
even derive its clock by multiplying the FSB clock?
Would most people have the FSB at the highest setting suported anyway,
and they'd have a CPU that supports it, so how would they overclock?
(they cna't up the FSB clock because it's already on the highest, and
they can't up the multiplier because it's properly locked)

also higher FSB = higher bandwidth = higher performance.

yeah, if it's greater width. i'm talking about speed only though.

Umm, say what? It's obvious that more throughput = more performance, and
throughput = bus width * bus speed, so increasing the bus speed (FSB)
obviously increases performance. Or do you think a Athlon running sync with
PC66 RAM (66MHz FSB, SDR, 64 bits wide) would perform just as well as the
identical CPU running sync with PC3200 RAM (200MHz FSB, DDR, 64 bits wide)?

oh yeah, I just realised that in a post in reply to that other Geezer
in the thread.
btw, Some software tells me that my RAM is operating at a multiple of
the processor speed. I can put my FSB=100 and have 266MHZ
DDR-SDRAM(actual speed 133MHz) So si sandra tells me it's a multiple
of my FSB.
Is it correct that RAM uses a multiplier too? It sure looks like it
from si sandra, though there is no option in the BIOS to set it, I can
only set the ram frequency. I thought that RAM derives its speed from
the FSB, the FSB is like the base clock, so it must multiply it,
strange that there's no option in the bios to set the ram multiplier.

try unlocking an A64 or a P3/P4

XP's yeah sure you can unlock them, but why? the higher the fsb the better

--
From Adam Webb, Overlag
www.tacticalgamer.com
CS:SOURCE server now active
"James Hanley" wrote in message
m...
"Michael Brown" wrote in message
...
James Hanley wrote:
"Adam Webb" wrote in message
...
it seems to me that nobody needs a high fsb. since they could just
push the multiplier really high.

you cant push the multiplier high because its locked on most modern
CPU's

nobody on an overclocking forum should be saying
"oh no, the multiplier is locked, what am I going to do"
Just like no technician is going to say, oh no, the file is 'hidden'
what am I going to do.

Better analogy: the technician saying "oh no, someone has wiped the disk
then turned it into slag in a blast furnace, what am I going to do?".
Given
that people have spent close to 6 years trying to unlock Intel CPUs (no
success) and about 1 year trying to unlock locked AMD chips (no
success),

6 years? - but there are loads of articles on unlocking AMD chips, i'm
sure I think I saw one for the AMD XP 1500+, that's less than 6 years
old isn't it?

The general view is
that both companies are using fuses inside the die, which can't be
altered
once set.

*******s.
So how can anybody overclock? Just by upping the FSB to whatever the
mobo supports?
I suppose that a CPU will have a built in multiplier at a fixed value,
and will assume a certain FSB speed. So if the FSB is lower then it's
underclocked. If it's higher then it's overclocked. Or does it not
even derive its clock by multiplying the FSB clock?
Would most people have the FSB at the highest setting suported anyway,
and they'd have a CPU that supports it, so how would they overclock?
(they cna't up the FSB clock because it's already on the highest, and
they can't up the multiplier because it's properly locked)

also higher FSB = higher bandwidth = higher performance.

yeah, if it's greater width. i'm talking about speed only though.

Umm, say what? It's obvious that more throughput = more performance, and
throughput = bus width * bus speed, so increasing the bus speed (FSB)
obviously increases performance. Or do you think a Athlon running sync
with
PC66 RAM (66MHz FSB, SDR, 64 bits wide) would perform just as well as
the
identical CPU running sync with PC3200 RAM (200MHz FSB, DDR, 64 bits
wide)?

oh yeah, I just realised that in a post in reply to that other Geezer
in the thread.
btw, Some software tells me that my RAM is operating at a multiple of
the processor speed. I can put my FSB=100 and have 266MHZ
DDR-SDRAM(actual speed 133MHz) So si sandra tells me it's a multiple
of my FSB.
Is it correct that RAM uses a multiplier too? It sure looks like it
from si sandra, though there is no option in the BIOS to set it, I can
only set the ram frequency. I thought that RAM derives its speed from
the FSB, the FSB is like the base clock, so it must multiply it,
strange that there's no option in the bios to set the ram multiplier.


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James Hanley wrote:

"Michael Brown" wrote in message ...

James Hanley wrote:

"Adam Webb" wrote in message
. ..

it seems to me that nobody needs a high fsb. since they could just
push the multiplier really high.

you cant push the multiplier high because its locked on most modern
CPU's

nobody on an overclocking forum should be saying
"oh no, the multiplier is locked, what am I going to do"
Just like no technician is going to say, oh no, the file is 'hidden'
what am I going to do.

Better analogy: the technician saying "oh no, someone has wiped the disk
then turned it into slag in a blast furnace, what am I going to do?". Given
that people have spent close to 6 years trying to unlock Intel CPUs (no
success) and about 1 year trying to unlock locked AMD chips (no success),


6 years? - but there are loads of articles on unlocking AMD chips, i'm
sure I think I saw one for the AMD XP 1500+, that's less than 6 years
old isn't it?

You didn't pay attention to what he wrote. The 6 years was with regard to
Intel processors and he said "about 1 year" with respect to AMD processors.



The general view is
that both companies are using fuses inside the die, which can't be altered
once set.


*******s.

It all started when unscrupulous resellers simply remarked lower speed
chips to higher speed ones so they could profit by selling cheap processors
at the higher price.

So how can anybody overclock? Just by upping the FSB to whatever the
mobo supports?

Correct. Except that Intel has now tried to lock the FSB.

I suppose that a CPU will have a built in multiplier at a fixed value,
and will assume a certain FSB speed. So if the FSB is lower then it's
underclocked. If it's higher then it's overclocked.

Correct

Or does it not
even derive its clock by multiplying the FSB clock?

It has no other choice.

Would most people have the FSB at the highest setting suported anyway,
and they'd have a CPU that supports it, so how would they overclock?
(they cna't up the FSB clock because it's already on the highest, and
they can't up the multiplier because it's properly locked)

That's why overclockerr's PICK the best processor to overclock, and a
motherboard that provides the ability to do so.


snip

"James Hanley" wrote in message
6 years? - but there are loads of articles on unlocking AMD chips,

Try finding one about unlocking Intel CPU's.

i'm sure I think I saw one for the AMD XP 1500+, that's less than 6
years old isn't it?

Read Michael's post again. The six years comment was in reference to Intel
stuff. The only modern Intel CPU's with variable multipliers are some of the
very latest Pentium M's and Pentium 4's, and even there the multiplier can't
be unlocked in the full sense of the word, the chip is shipped with a range
of multipliers accessible.

So how can anybody overclock? Just by upping the FSB to
whatever the mobo supports?

Or whatever the CPU and memory will tolerate, whichever comes first. As has
been said, locked multipliers aren't a problem, as raising the FSB is the
best way to do it anyway.

I suppose that a CPU will have a built in multiplier at a fixed
value

Correct, with the caveat that on many AMD chips, and old Intel ones, it can
be changed by one means or another.

and will assume a certain FSB speed.

Yes and no. The manufacturer, whether it be Intel or AMD, will decide on an
FSB, but rather than the CPU making assumptions, it will *tell* the
motherboard what FSB to select. Most motherboards with any enthusiast
pretensions will be able to override this though.

So if the FSB is lower then it's underclocked. If it's higher
then it's overclocked.

Yes and yes.

Would most people have the FSB at the highest setting suported
anyway,

No way. Most of the people who go out of their way to build an overclocked
system will deliberately choose a CPU-motherboard-memory platform that
offers headroom for overclocking. Intel CPU's are a case in point: the
"slower"/cheaper CPU's with lower multipliers tend to make better
overclocking candidates than the "faster" ones.

Most motherboards will run much faster than their officially supported
speeds anyway. Just look at the old 440BX Pentium II/III chipset, which was
only ever designed to run at 100MHz FSB, but would, in practice, work
perfectly stably at 166 or higher. The situation today is no different.
Intel's Canterwood and Springdale chipsets are designed for operation at
200MHz FSB, but will in practice run at over 300.

(they cna't up the FSB clock because it's already on the highest,
and they can't up the multiplier because it's properly locked)

There's a big difference between the highest speed that's "officially"
supported by a chipset and what it will do in practice. There are also
plenty of examples where you might want to buy a "slower" CPU because it
makes a better overclocking candidate.

btw, Some software tells me that my RAM is operating at a multiple
of the processor speed. I can put my FSB=100 and have 266MHZ
DDR-SDRAM(actual speed 133MHz)

Trouble with this approach, especially on modern platforms, is that setting
the memory bus faster than the frontside bus doesn't get you anything, as
there's a bottleneck in the connection between the memory and the processor,
which you only raise by raising the FSB.

Is it correct that RAM uses a multiplier too?

Yes.

It sure looks like it from si sandra, though there is no option
in the BIOS to set it, I can only set the ram frequency.

It *is* a multiplier, despite the confusing labelling. The "100MHz" setting
corresponds to a 1:1 FSB:memory bus multiplier. The "133MHz" setting
corresponds to 1:1.3333 FSB:memory ratio. One thing to add though is that
you have to be careful with Sandra and taking what she says as gospel, as
like many women, she often misleads and sometimes downright lies.

strange that there's no option in the bios to set the ram multiplier.

It is exactly that option, it's just that your particular motherboard
manufacturer has chosen to present it in a slightly different manner. Many
motherboard makers list it in their BIOSes as what it is - a multiplier (or,
as is often the case, a divider).
--


Richard Hopkins
Cardiff, Wales, United Kingdom
(replace .nospam with .com in reply address)

The UK's leading technology reseller www.dabs.com
Get the most out of your digital photos www.dabsxpose.com

James Hanley wrote:

it seems to me that nobody needs a high fsb. since they could just
push the multiplier really high.

I can see the greatness of ddr since the same speed processor can
read/write twice as much per cycle. (i assume that the cpu has to be
ddr to receive or write double)

How is it you can see the benefit to 'read/write twice as much per cycle'
yet not see any benefit to more of the cycles?

The CPU communicates to everything through the FSB, and that includes the
memory, so the speed of it directly affects how fast the processor can
communicate. And since the vast majority of that communication is fetching
instructions from memory, it affects how fast it can process them.

David Maynard wrote in message ...
James Hanley wrote:

it seems to me that nobody needs a high fsb. since they could just
push the multiplier really high.

I can see the greatness of ddr since the same speed processor can
read/write twice as much per cycle. (i assume that the cpu has to be
ddr to receive or write double)

How is it you can see the benefit to 'read/write twice as much per cycle'
yet not see any benefit to more of the cycles?

The CPU communicates to everything through the FSB, and that includes the
memory, so the speed of it directly affects how fast the processor can
communicate. And since the vast majority of that communication is fetching
instructions from memory, it affects how fast it can process them.

The FSB is not THE ONLY THING that affects the speed. The
Multiplier*FSB create the speed. The Processor multiplies the FSB,
and the RAM multiplies the FSB. I am saying that the multiplier can
be increased, so low FSB speed doesn't matter.