Bus speed calc?

"Ed" wrote in message
...
Don't know where to ask this but I'm writing a little FSB x Multiplier
Calc program and want to get the bus speed as near as possible so the
expected CPU speed is closer to what you would expect when using them on
a motherboard.

When I look at normal bus speed settings I notice 133 = 133.33 and 166 =
166.66, but how would I figure out non-standard bus speeds?

Inputs on my calc look like this,
FSB Starting Freq. (100 to 299)
FSB Ending Freq. (101 to 300)
CPU Multiplier (5 to 24)

Example of output...
166.66 x 12.5 = 2083.25
167.66 x 12.5 = 2095.75
168.66 x 12.5 = 2108.25
169.66 x 12.5 = 2120.75
170.66 x 12.5 = 2133.25

Probably silly but I write a lot of silly little utilities. ;p
Cheers,
Ed

Took me a minute, but I figured out what you're doing. You're trying to
write a program that lets the user set a range of bus speeds to use, so they
can figure out how fast the CPU is when they overclock the bus speed, but
with a range.

*IF* this is the purpose, then what I would include into this program is a
selector to choose, 1) AMD/Intel 2) Model of CPU within selection of #1 3)
"Normal" CPU speed [not an option, naturally, but an output]

Based on the model, you can determine what the multiplier is, since after
all you are writing a bus speed calc, not a multiplier calc, so it is
probably not something where the user is able to change the multiplier

The thing to notice about the actual FSB speed is that, well, I'll use my
antiquated system based on an Abit KT7-RAID (yes, the original with 100mhz
bus to demonstrate. With the bus speeds, everything is based around 33
1/3MHz. It just so happens when you get 3 of these, it is 100.00MHz. If
you had 4, it is 133 1/3MHz, so and so forth.

It is the custom bus speeds, like 125MHz or 111MHz that are different.
AFAIK, these are actually 125.00MHz & 111.00MHz. Now, I'm unsure if these
two examples are the .00MHz because of the fact they are after the 100 but
before 133 1/3 or if it is just because.... What I would do is if I had a
133MHz CPU & board is just set the FSB to say 134MHz, run WCPUID, and see if
it reports it as 134.00 or 134.33MHz. Sadly, I think this is where you are
stuck My complete and utter guess, is that 134 = 134.33, and 167 =
167.66. Likewise, a 201MHz bus is really 201.00MHz, due to the fact 200 is
33 1/3 x 6, and that leaves no decimals.

It is also something rather important, too, since even with a 12.5x
multiplier, .33MHz off is 4MHz, and with .66MHz off, it is now 8MHz. While
this wouldn't be anything to necessitate a new product, it is something that
diehard overclockers would be interested in, and someone who would end up
using this calc, if I have perceived it correctly.

Anonymous Joe wrote:

"Ed" wrote in message
...

Don't know where to ask this but I'm writing a little FSB x Multiplier
Calc program and want to get the bus speed as near as possible so the
expected CPU speed is closer to what you would expect when using them on
a motherboard.

When I look at normal bus speed settings I notice 133 = 133.33 and 166 =
166.66, but how would I figure out non-standard bus speeds?

Inputs on my calc look like this,
FSB Starting Freq. (100 to 299)
FSB Ending Freq. (101 to 300)
CPU Multiplier (5 to 24)

Example of output...
166.66 x 12.5 = 2083.25
167.66 x 12.5 = 2095.75
168.66 x 12.5 = 2108.25
169.66 x 12.5 = 2120.75
170.66 x 12.5 = 2133.25

Probably silly but I write a lot of silly little utilities. ;p
Cheers,
Ed


Took me a minute, but I figured out what you're doing. You're trying to
write a program that lets the user set a range of bus speeds to use, so they
can figure out how fast the CPU is when they overclock the bus speed, but
with a range.

*IF* this is the purpose, then what I would include into this program is a
selector to choose, 1) AMD/Intel 2) Model of CPU within selection of #1 3)
"Normal" CPU speed [not an option, naturally, but an output]

Based on the model, you can determine what the multiplier is, since after
all you are writing a bus speed calc, not a multiplier calc, so it is
probably not something where the user is able to change the multiplier

The thing to notice about the actual FSB speed is that, well, I'll use my
antiquated system based on an Abit KT7-RAID (yes, the original with 100mhz
bus to demonstrate. With the bus speeds, everything is based around 33
1/3MHz. It just so happens when you get 3 of these, it is 100.00MHz. If
you had 4, it is 133 1/3MHz, so and so forth.

Actually, the FSB speed is set by the motherboard's clock chip, and is
not neccessarily 'based around 33 1/3Mhz'.

For example, the ICS9250CF-08 clock generator on my Asus P2B-DS,
according to the manufacturer's datasheet, runs at 66.8Mhz FSB / 33.4Mhz
PCI on the 66Mhz setting, 100.3Mhz FSB / 33.43Mhz PCI on the 100Mhz
setting, and 133Mhz FSB / 33.25Mhz PCI on the 133Mhz setting.

The clock chip derives all it's outputs from an external 14.318Mhz
crystal, a frequency which doesn't divide nicely into any of the
standard bus clocks, and the chip also has to generate a 24Mhz clock for
the Super I/O chip, and 48Mhz for USB. All things considered, it does
rather well to keep all the clocks within a Mhz of their nominal
frequencies :-)

It is the custom bus speeds, like 125MHz or 111MHz that are different.
AFAIK, these are actually 125.00MHz & 111.00MHz. Now, I'm unsure if these
two examples are the .00MHz because of the fact they are after the 100 but
before 133 1/3 or if it is just because.... What I would do is if I had a
133MHz CPU & board is just set the FSB to say 134MHz, run WCPUID, and see if
it reports it as 134.00 or 134.33MHz. Sadly, I think this is where you are
stuck My complete and utter guess, is that 134 = 134.33, and 167 =
167.66. Likewise, a 201MHz bus is really 201.00MHz, due to the fact 200 is
33 1/3 x 6, and that leaves no decimals.

It is also something rather important, too, since even with a 12.5x
multiplier, .33MHz off is 4MHz, and with .66MHz off, it is now 8MHz. While
this wouldn't be anything to necessitate a new product, it is something that
diehard overclockers would be interested in, and someone who would end up
using this calc, if I have perceived it correctly.