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some bus speed questions

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Anonymous
a b B Homebuilt system
a b à CPUs
April 13, 2004 12:20:20 PM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

Hi
I am reading different articals about the bus speed.. and I came to
some points that I do not understand, could you please help me.. these
are the points I do not understand

1) <quote> FSB speed setting is determind by the CPU </quote>
My question what does that mean?? does it mean CPU decide the speed of
the FSB?? is not true that FSB has its own clock and that clock decide
the speed of the FSB?

2) Does the CPU has an internal clock or it uses the FSB clock
(external clock) + the multipler to generate what is called internal
clock??

3) OverClock, does that term mean is to increase the FSB speed?? would
that effect the momory bus speed??

I would appreciate your help in advanced..

More about : bus speed questions

Anonymous
a b B Homebuilt system
a b à CPUs
April 14, 2004 2:09:40 AM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

On Tue, 13 Apr 2004 08:20:20 -0700, esara wrote:

> Hi
> I am reading different articals about the bus speed.. and I came to
> some points that I do not understand, could you please help me.. these
> are the points I do not understand
>
> 1) <quote> FSB speed setting is determind by the CPU </quote>
> My question what does that mean?? does it mean CPU decide the speed of
> the FSB?? is not true that FSB has its own clock and that clock decide
> the speed of the FSB?
>
The FSB speed (clock) is generated by the MB. Most MB allow you to et this
either in the bios, by a jumper on the MB, or both. Very few MB's may not
have a setting and will use what's defined as default by the FSB sense
pins of the cpu. So basically, the quote is only refering to MB's that
don't support a FSB setting.

> 2) Does the CPU has an internal clock or it uses the FSB clock (external
> clock) + the multipler to generate what is called internal clock??
>
It uses the FSB clock x multiplier for cpu clockspeed.

> 3) OverClock, does that term mean is to increase the FSB speed?? would
> that effect the momory bus speed??
>
Overclock generally means running the CPu faster than it's rated speed.
This can be accomplished by raising the FSB speed, raising the multiplier,
or both. Personally, I don't really consider a cpu overclocked until I go
over the the maximum rated speed for the core, not the model.
As for the memory bus, it depends on the MB. Some allow async operations
and some don't. Most newer boards do I believe. The one catch is that
while you can set the mem bus speed seperately, it may increase too if you
set the FSB to an in between value. IOW's, my FSB set to 180 and mem bus
set to 166 will run the mem bus at 180. My FSB set to 200 and mem bus set
to 166 will run the me bus at 166. 201=167, etc.

--
Abit KT7-Raid (KT133) Tbred B core CPU @2400MHz (24x100FSB)
http://mysite.verizon.net/res0exft/cpu.htm
Anonymous
a b B Homebuilt system
a b à CPUs
April 16, 2004 9:50:19 PM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

FSB Speed is a little tricky. Take a Athlon 2400+ as an example. The
FSB speed is 266Mhz. However the actually clock speed generated by
the clock generator on the motherboard should be set to 133Mhz. AMD
motherboards and especially the AMD processor have 2 Actions performed
for every clock cycle. Because of this, The FSB is 2 X 133 = 266.

How this is done on a P4 Processor is different than on an AMD
processor. This is because both the AMD and the Intel processors
produce the same results, but they do this using a different
Architecture or chip design. The 800Mhz FSB on a P4 is achieved at a
200mhz clock but it is quad pumped.

Therefore the FSB is 4 X 200 = 800.

>Hi
>I am reading different articals about the bus speed.. and I came to
>some points that I do not understand, could you please help me.. these
>are the points I do not understand
>
>1) <quote> FSB speed setting is determind by the CPU </quote>
>My question what does that mean?? does it mean CPU decide the speed of
>the FSB?? is not true that FSB has its own clock and that clock decide
>the speed of the FSB?
>
>2) Does the CPU has an internal clock or it uses the FSB clock
>(external clock) + the multipler to generate what is called internal
>clock??
>
>3) OverClock, does that term mean is to increase the FSB speed?? would
>that effect the momory bus speed??
>
>I would appreciate your help in advanced..
Anonymous
a b B Homebuilt system
a b à CPUs
April 17, 2004 10:57:33 AM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

On Fri, 16 Apr 2004 17:50:19 -0500, Last Boy Scout wrote:

> FSB Speed is a little tricky. Take a Athlon 2400+ as an example. The
> FSB speed is 266Mhz. However the actually clock speed generated by
> the clock generator on the motherboard should be set to 133Mhz. AMD
> motherboards and especially the AMD processor have 2 Actions performed
> for every clock cycle. Because of this, The FSB is 2 X 133 = 266.
>
> How this is done on a P4 Processor is different than on an AMD
> processor. This is because both the AMD and the Intel processors
> produce the same results, but they do this using a different
> Architecture or chip design. The 800Mhz FSB on a P4 is achieved at a
> 200mhz clock but it is quad pumped.
>
> Therefore the FSB is 4 X 200 = 800.
>
Leave it to the government to only get it half right.:-)
Bus speeds are measured by the clock rate in Hz.
Data rates are measured in throughput using bps or Bps.
You are taking the 400/800 data rates and giving them a bus speed MHz
rating which is just wrong.
A ddr (K7) bus of 200MHz has a data rate of 400Mbps per line, or a
thoughput speed of approx. 3200MBps assuming a 64 bit wide bus. And qdr
(P4) would be 6400MBps.

See The Real Front side Bus in link below.

--
Abit KT7-Raid (KT133) Tbred B core CPU @2400MHz (24x100FSB)
http://mysite.verizon.net/res0exft/cpu.htm
!