celeron running faster than the mobo support?

[Guest_imported]

I come across a product (a slot1 card) saying that
it can run celeron cpu at 1.2G even on a mobo that
only support 100(FSB) x8 (frequency multiplier).
It this possible? Can anyone please comment on
that. The mobo in question is ASUS P2B.

 

[dakota81]

You are limited by what the motherboard supports.

Check Asus' website for any BIOS updates. Often a manual will say it will support the latest cpu at the time of printing - but they have built in support for future processor speeds.

 

[fedto]

This may sound wierd, but yea the processor can run that fast on a 100mhz FSB, BUT the system will only show the max the mobo can handle, be it 600 or 800. One good example would be an upgrade processor I once had on a 486 system with a fsb of 25mhz. The processor internally ran at 133mhz, but the system could only run a max of 100mhz.

 

[Guest_imported]

I am sorry, I still don't get it.

You two guys are saying different things or am
I misinterpreting.

dakota81 says that I will be limited by what the
motherboard supports and

fedto says that the system will only show the max
the mobo can handle, be it 600 or 800
(and cpu running at 1.2G ?)

If it happens as what fedto says, I am OK but how
am I going to prove that it is infact running at 1.2G
(I might have to show my boss that he is getting
what he paid for)

 

[REIGNGK]

you can download wcpuid. I beleive that it shows the actual speed of the cpu. Hope i helped!

 

[stevieblunder]

I have this issue. My old (Sony Vaio) Pheonix BIOS was written to recognise nothing faster than 500MHz. So when it boots, that's what it figures the CPU is. I did download the latest BIOS from Sony. This is an old 66MHz FSB MOBO, but I have a 700MHz Celeron (700/128/66) in it now. (This chips uses a *10.5 multplier, so it would not work on a 100MHz FSB, 66*10.5=700)

I was worried that the BIOS would not handle the L2 cache, but it does. I have used "PowerLeap CPU control panel", "Dr. Hardware", and dxdiag.exe (part of the MS direct-X stuff). All three say I have a 700MHz cpu and the cache is enabled, so not to worry if the BIOS boot screen is wrong.

 

[dakota81]

Yeah, most motherboards have support for cpu's faster than what their manuals state - at the time the manual was printed, they listed the fasted cpu that existed. Manufactures usually build their hardware for clock multipliers beyond what exists, but a lot of times because the cpu's don't exist yet, they don't have the bios support written for them - hence a lot of times you will find a bios update that allows faster cpu's.

Bottom line is, system speed is driven off a clock - and the clock is a part of the motherboard. Therefore the system speed is limited by what the motherboard can handle, not what the cpu can handle.

If you halve the FSB, you are going to halve the cpu speed - the cpu can't magically retain its max speed, it doesn't really have a concept of time, it just knows that it must update the data on the edges of the clock pulses. If the clock (controlled by the motherboard) says to run at 800MHz, there's nothing a 1.2GHz cpu can do except to run at 800MHz.

 

[Guest_imported]

dakota81,
That's exactly what I am thinking, but the guys from
the manufacturer says different, below is the exact quote :

The clock multiplier is determined by the CPU. Motherboards are more
limited by the voltage of the CPU than anything else. Our adapter
adjusts this voltage and timing before it gets to the motherboard. Thus
allowing you to use a 1.2 GHz Celeron, for example. If you have any
other questions let me know.

Maybe my English is so poor that I misinterpret it. What do you say

 

[stevieblunder]

I looked into this at Intel's web site. By looking at some data sheets, it looks like P6 (=~PII) based Celerons use 4 pull-ups at reset to set the CPU multiplier, up to 8x. But PIII based Celerons "do not support" variable multipliers, but, they do have two FSB frequency select outputs, actually I/O pins that can be read by the bios.

So if you are using a PIII based Celeron, your CPU core frequecy is not limited to 8X the FSB, and I assume it will ignore any MOBO multiplier settings.

I recomend your download Intel data sheets. They even have have sample PC schematics for PIIIs and earlier. The same is true of most chips vendors. Via does not seem to have the detailed data on line that they used to, or it just may be that you have to look harder. Try their ftp site.

Some companies make you "register" to get their data. They should know, that doing so is a pain in the ass, and when I can find a chip that meets my needs, without registering to review it, then I'm not going to bother looking at those that I have to register to get data. And some times the reason for registering customers is an attempt to avoid patent conflicts. But their compeditors have lots of motivation to go to the trouble to aquire compeditor product data, and it's an indication to real customers that maybe they should not invest in using parts that may become unavailable due to legal problems.

BTW Tek-tips people, You may notice that I am not just a "technical user", but tek-tips did not have any hardware catagories for members. Tek-tips should have "hardware technician/engineer" as an member type option.

Cheers,
Steve