The FSB and the CPU

[Tim]

Archived from groups: alt.comp.hardware.overclocking.amd (More info?)

I have a few questions regarding the FSB and how it affects the CPU ...

1) Are FSB frequency pulses generated from within the CPU itself or from
somewhere else? Where is the oscillator (if that's what it's called), and
where is the multiplier?

2) Hypothetically, if you have a processor with a 1GHz speed rating, which
it achieves through a 100 MHz FSB and a 10x multiplier, what happens when
you achieve that 1GHz using an overclocked FSB and a lower multiplier? Does
it put a strain on the CPU, even though the final CPU speed is still running
at its intended frequency? I know that an overclocked FSB can put a strain
on other components but I never heard it pertain to processors. What about
the CPU's link to the northbridge, would it put a strain on that?

Thanks in advance.

 

[peter]

Archived from groups: alt.comp.hardware.overclocking.amd (More info?)

FSB (Front Side Bus) Frequencies are created by the chips on the mobo,
normally 133, 166,or 200 Mhz this is the speed that the memory works on
except it's double pumped eg DDR400 runs at 200Mhz and DDR2700 runs at 166
Mhz.

To get the final speed you do FSB x Multiplier, 200 Mhz x 11 is almost the
same speed as 166 x 13. The latter is often better as the RAM is running
faster.

This puts no extra strain on the CPU, nForce Mobos lock the PCI and AGP to
33/66 Mhz so it would not affect these. Some mobos use dividers to make
these frequencies as close as possible.

The northbridge is under more strain but many boards are rated much higher
so it is within manufacturers specs.

Peter

"Tim" <argybargy@hotmail.com> wrote in message
news:2iuj6gFrnjc6U1@uni-berlin.de...
> I have a few questions regarding the FSB and how it affects the CPU ...
>
> 1) Are FSB frequency pulses generated from within the CPU itself or from
> somewhere else? Where is the oscillator (if that's what it's called), and
> where is the multiplier?
>
> 2) Hypothetically, if you have a processor with a 1GHz speed rating, which
> it achieves through a 100 MHz FSB and a 10x multiplier, what happens when
> you achieve that 1GHz using an overclocked FSB and a lower multiplier?
Does
> it put a strain on the CPU, even though the final CPU speed is still
running
> at its intended frequency? I know that an overclocked FSB can put a
strain
> on other components but I never heard it pertain to processors. What
about
> the CPU's link to the northbridge, would it put a strain on that?
>
> Thanks in advance.
>
>

 

[Guest]

Archived from groups: alt.comp.hardware.overclocking.amd (More info?)

Tim wrote:
> I have a few questions regarding the FSB and how it affects the CPU ...
>
> 1) Are FSB frequency pulses generated from within the CPU itself or from
> somewhere else? Where is the oscillator (if that's what it's called), and
> where is the multiplier?

You'll have a programmable oscillator chip on the motherboard or built into
the chipset.

The multiplier is "inside" the CPU.

> 2) Hypothetically, if you have a processor with a 1GHz speed rating, which
> it achieves through a 100 MHz FSB and a 10x multiplier, what happens when
> you achieve that 1GHz using an overclocked FSB and a lower multiplier?

You can get more data to the CPU.

> Does it put a strain on the CPU, even though the final CPU speed is still
> running at its intended frequency?

Well, if the core can do 1GHz, then the FSB side of things much much slower,
so I'm guessing it should be ok, but have an incling that it does indeed put
"more strain" on the CPU, bits of the CPU, not all of it.

> I know that an overclocked FSB can
> put a strain on other components but I never heard it pertain to
> processors. What about the CPU's link to the northbridge, would it put a
> strain on that?

That IS the FSB.

The "strain" on other components is usually because you are overclocking the
PCI and AGP buses (most chipsets produce those clocks using a divider from
the FSB frequency). However, there are chipsets (nForce2/3) that generate a
separate clock for the PCI and AGP, allowing you to run your FSB at any
speed and the PCI bus at the correct speed.

Ben
--
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Questions by email will likely be ignored, please use the newsgroups.
I'm not just a number. To many, I'm known as a String...

 

[Guest]

Archived from groups: alt.comp.hardware.overclocking.amd (More info?)

Peter wrote:
> FSB (Front Side Bus) Frequencies are created by the chips on the mobo,
> normally 133, 166,or 200 Mhz this is the speed that the memory works
> on except it's double pumped eg DDR400 runs at 200Mhz and DDR2700
> runs at 166 Mhz.
>
> To get the final speed you do FSB x Multiplier, 200 Mhz x 11 is
> almost the same speed as 166 x 13. The latter is often better as the
> RAM is running faster.

Don't you mean the former?
--
~misfit~


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[Tim]

Archived from groups: alt.comp.hardware.overclocking.amd (More info?)

"Ben Pope" <spam@hotmail.com> wrote in message
news:2j6g77Fu12fkU1@uni-berlin.de...
> Tim wrote:
> > I have a few questions regarding the FSB and how it affects the CPU ...
> >
> > 1) Are FSB frequency pulses generated from within the CPU itself or from
> > somewhere else? Where is the oscillator (if that's what it's called),
and
> > where is the multiplier?
>
> You'll have a programmable oscillator chip on the motherboard or built
into
> the chipset.
>
> The multiplier is "inside" the CPU.
>
> > 2) Hypothetically, if you have a processor with a 1GHz speed rating,
which
> > it achieves through a 100 MHz FSB and a 10x multiplier, what happens
when
> > you achieve that 1GHz using an overclocked FSB and a lower multiplier?
>
> You can get more data to the CPU.
>
> > Does it put a strain on the CPU, even though the final CPU speed is
still
> > running at its intended frequency?
>
> Well, if the core can do 1GHz, then the FSB side of things much much
slower,
> so I'm guessing it should be ok, but have an incling that it does indeed
put
> "more strain" on the CPU, bits of the CPU, not all of it.
>
> > I know that an overclocked FSB can
> > put a strain on other components but I never heard it pertain to
> > processors. What about the CPU's link to the northbridge, would it put
a
> > strain on that?
>
> That IS the FSB.
>
> The "strain" on other components is usually because you are overclocking
the
> PCI and AGP buses (most chipsets produce those clocks using a divider from
> the FSB frequency). However, there are chipsets (nForce2/3) that generate
a
> separate clock for the PCI and AGP, allowing you to run your FSB at any
> speed and the PCI bus at the correct speed.
>

Very useful info. Thanks.