Re: fsb of older cpu

[Stefan Smietanowski <stesmi@stesmi.com>]

>>> Hello,
>>> is there a way to measure/change the fsb of a PII/233/Tonga/440BX while
>>> running linux? Google has no answer...
>>
>>
>>
>> This is the only one I know about, but it has support for a few 
>> boards/pll's only.
>>
>> http://home.iprimus.com.au/mccvals/mvpll/
>>
>> Hope it helps,
>>     Bernd
> 
> 
> Hello and thank you for your answer. I determined that this cpu has a 
> fsb of
> 66MHz. The reason for my question was that i want to underclock the cpu.
> I think it would be better to change the multiplier instead of changing 
> the fsb.
> Therefore i read the msr register 0x02ah, tilted bit 27 and wrote it 
> back, but
> the cpu clock is still the same. Why does that not work? Is it possible to
> change the multiplier at runtime at all?
> 

I'm no expert on the subject but as I recall the processor sets the
internal clock (derived from fsb+multiplier) on startup so no matter
what you do do the running cpu it won't change it.

// Stefan