[linux-audio-user] CPU clock - beware

[Rick B]

tim hall wrote:

>Last Saturday 24 July 2004 15:12, Stefan Scheffler was like:
>  
>
>>hmm ... are you sure about the type of processor? AFAIK only Celerons
>>+700 mhz support a 100mz fsb.
>>    
>>
>
>I'm just reading the motherboard manual.
>
>  
>
>>Intel has a utility to check cpu information bus speed and so on ..
>>sadly it's windows/dos only:
>>http://downloadfinder.intel.com/scripts-df/Product_Filter.asp?ProductID=441
>>    
>>
>
>Won't be much use to me then ;-)
>
>Thanks for the other suggestions tho'
>
>  
>
>>>I think it's probably more a question of me explaining badly. I think I've
>>>just set it to the maximum I can get with this mobo & processor. The one
>>>weirdness is that the processor is now being detected as 900MHz, which is
>>>not true. Perhaps the 1800 bogomips reading is, I don't know.
>>>      
>>>
>>now that is uh  ... interesting  ... so within two days you like almost
>>quadrupled your processor speed .. congratulations :D
>>    
>>
>
>Yeah, basically I suspect I've been driving with the handbrake on :-]
>
>  
>
>>could you post the output of "cat /proc/cpuinfo"? I'd love to see that. :)
>>    
>>
>
>sure:
>~$ cat /proc/cpuinfo
>processor       : 0
>vendor_id       : GenuineIntel
>cpu family      : 6
>model           : 8
>model name      : Celeron (Coppermine)
>stepping        : 6
>cpu MHz         : 896.977
>cache size      : 128 KB
>fdiv_bug        : no
>hlt_bug         : yes
>f00f_bug        : no
>coma_bug        : no
>fpu             : yes
>fpu_exception   : yes
>cpuid level     : 2
>wp              : yes
>flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca 
>cmov pat pse36 mmx fxsr sse
>bogomips        : 1789.13
>
>  
>
>>just FYI:
>>"model name      :" should tell you the name and aometimes the design
>>speed of the cpu
>>"cpu MHz" the real current speed
>>"bogomips" issome weird timing value I have no idea what it means exactly
>>    
>>
>It's a semi-arbitrary benchmarking value, usually twice the processor speed. 
>AFAIU.
>
>Last Saturday 24 July 2004 16:33, Matthew Barber was like:
>  
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>>Be careful doing something like that, especially with old boards.  I
>>think setting the fsb clock to "no man's land" will set the pci clock
>>(and AGP if you have AGP on your board) to something unusable, unless
>>BIOS locks the PCI/AGP clock to a certain range of values.  PCI
>>generally wants to run at about 33Mhz (unless you have a very new board
>>with PCI-X or some such), and AGP at 66Mhz, and these values will
>>generally be a fraction of the fsb.  So if your fsb is 66Mhz, PCI will
>>be 1/2FSB.  If it's 100Mhz, PCI will be 1/3.  Setting it to 75Mhz may
>>cause it to still be in the 66Mhz realm as far as the division is
>>concerned, and set PCI to around 38Mhz, which may cause a lot of
>>problems.  I know some BIOS will take care of this by locking AGP and
>>PCI to a certain value, but I wouldn't count on it with an older
>>board/bios.
>>    
>>
>
>This is what I guessed, I'm using the values specified in the manual for a 
>Coppermine FC-PGA 600, so:
>at 3x clock ratio I get:
>CPU (I assume this is FSB) 100
>PCI 33
>AGP 66
>The display cache runs at 100MHz too, a 1:1 ratio seems logical.
>One of the reasons I only have 192MB of RAM is because I have already been 
>fussy enough only to use memory that is supposed to run at 100MHz too.
>No-man's land FSBs are only relevant if overclocking, which is not the object 
>of the exercise for me. I'm trying to optimise.
>
>I don't think I'm doing _too_ badly.
>
>Last Saturday 24 July 2004 17:49, Ryan Underwood was like:
>  
>
>>Where?  Is there an online copy of this manual?
>>    
>>
>
>I found one here:
>http://www.motherboards.org/mobot/manuals/All/0/50/
>http://english.aopen.com.tw/products/mb/MX3WPro-V.htm
>
>I think I might read it now. I'm a bit confused as to why my system thinks 
>it's running a 896MHz CPU, But so far there's no overt signs that it isn't 
>happy, so I'll prod it a bit and see ;-)
>
>cheers
>
>tim hall
>
>
>  
>
Yeah that's close enough to 900mhz for me. Some cpu's are noted as being 
good overclockers, but, hell, that's a free 50% overclock! The new sweet 
spot for OCer's is the mobile athlon 2500/2600 (~$90US), out of the box 
they are ~1800 to 1900mhz and are easily hitting 2500mhz on air cooling 
with just a little extra voltage. The Pentium 2.4b's were easily hitting 
3Ghz.

                 Rick B