PCI divider @ 42??!

trox

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Oct 22, 2003
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Hi guys,

I just acquired a P3-1.266 ghz 512k cache and I put it on my Asus TUSL2-C (b4 it was p3-700E @952). I immediately overclocked it to 1.5ghz (158/158/37) and everything was stable. <b>I then tried 1.6ghz, setting is 169/128/42.</b> and everything was stable also. I already run prime95 24hrs without any problems. Run many games for hours, memtest86, hot cpu tester pro for 6 hrs so far no errors found.
But my question is this, is it safe to set the PCI divider at 42? My Tusl2-c doesn't have a pci lock and i'm afraid i might fry my pci / agp components.

Here is my complete rig:

Asus TUSL2-C, rev. 1.04, bios 1014 beta 001
P3s-1.26 ghz (512k) @ 1.6ghz
Globalwin CAK4-88T with Tt smartfan II
2 x 128MB apacer cl2 pc133 sdram
1 x 256MB pqi cl3 pc133 sdram
Asus V7100 gef2mx 400 64mb agp
creative audigy
pinnacle pctv
2 x 40gb hd 72k rpm
1 liteon dvd
1 liteon cdrw
1 outake fan @ 3,5k rpm
2 intake fan Tt smartfan II
enermax dual fan 350w psu

full load @ 45, idle @ 40 using artic silver 3

do i have to lower my settings / clock speed just to lower my pci divider? been running like this for 2 wks now. Any advice will be highly appreciated.

thanks in advance
 

scottchen

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It's very bad keep it under 40 so 39 maximum as a rule of thumb.

-Intel PIV 2.6C @ 3.51G -Asus P4P800 -OCZ Copper 2x256 4000EL memory @ 270mhz 2.5-4-4-8 -Sapphire 9800pro @ 490/780 -SB audigy -120G Maxtor Diamond Plus9 S-ATA150 hdd -450 Enermax PSU
 

Crashman

Polypheme
Former Staff
IN my experience 41-42MHz is the limit for many PCI devices, some are fussier though

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pIII_Man

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i ran 42mhz pci on my BX machine for quite a while with no problems. Its hit or miss, probably the first sign of something going wrong would be drive corruption, IMMEDIATLY if you see this occuring, back off.


If it isn't a P6 then it isn't a procesor
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pIII_Man

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did i say that? There is no max it all depends how well your pci cards/hard drive take the speed, if you dont have problems you'll be fine.


If it isn't a P6 then it isn't a procesor
110% BX fanboy
 

scottchen

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When I had my KT400 system, my Sound card didn't like anything above 39, it made loud screeches at 40.

-Intel PIV 2.6C @ 3.51G -Asus P4P800 -OCZ Copper 2x256 4000EL memory @ 270mhz 2.5-4-4-8 -Geforce2 MX400(i know i know) -SB audigy -120G Maxtor Diamond Plus9 S-ATA150 hdd -450 Enermax PSU
 

trox

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Oct 22, 2003
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well, right now my pci devices are fine with 42, but would I really damage / burn my pci devices at that divider? If only data corruption may occur and no hardware damage, then maybe i'll take a chance on it, see how long will my devices take it. what do you think? is there a documented or reported damage to devices or even motherboard when set at high settings? tnx.
 

pIII_Man

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I have yet to hear of long term dammage, just data corruption or devices that refuse to work, but when set back to more managable pci speeds are just fine.

I have noticed that as technology advances components are less able to be run at higher pci/agp bus speeds.


If it isn't a P6 then it isn't a procesor
110% BX fanboy
 

pIII_Man

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I have yet to hear of long term dammage, just data corruption or devices that refuse to work, but when set back to more managable pci speeds are just fine.

I have noticed that as technology advances components are less able to be run at higher pci/agp bus speeds.


If it isn't a P6 then it isn't a procesor
110% BX fanboy
 

scottchen

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Then why the hell they make the AGP/PCI frequency adjustable? Are they f*cking retarded?

-Intel PIV 2.6C @ 3.51G -Asus P4P800 -OCZ Copper 2x256 4000EL memory @ 270mhz 2.5-4-4-8 -Geforce2 MX400(i know i know) -SB audigy -120G Maxtor Diamond Plus9 S-ATA150 hdd -450 Enermax PSU
 

pIII_Man

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huh? Because at frequencies cards are not designed to run at a factor called skew comes into play. Basically they have a tollerance of how long it takes for a signal to get from place to place, if you run at a faster frequency there is less time to wait so eventually becuase no design or build can be perfect signals start running asynchronous to eachother. For example 1 packet of data comming from the agp card take 100ms to get to the NB and the other takes 107ms you will be left with data corrupion and thus a card that works improperly. However once you set the frequencies back a bit everything is peachy again, i have yet to hear of someone killing a pci card because of a high pci bus speed.

The next time you look at your mobo closely, take a hard look at the PLL you will see a lot a squiggly traces comming out of it, this is so two components running synchro to eachother get the timming signal at about the same time thus avoiding skew (at least at the designed frequencies).

The reason cards such as scsi and raid adapters don't normally like high pci frequencies is because they have much tighter tolerances to when signals should come and go, thus they are easily effected by skewed signals.


If it isn't a P6 then it isn't a procesor
110% BX fanboy
 

scottchen

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I love the nForce2 and i865pe or better chipsets they could lock it so it won't bug us when we're overclocking.

-Intel PIV 2.6C @ 3.51G -Asus P4P800 -OCZ Copper 2x256 4000EL memory @ 270mhz 2.5-4-4-8 -Geforce2 MX400(i know i know) -SB audigy -120G Maxtor Diamond Plus9 S-ATA150 hdd -450 Enermax PSU
 

pIII_Man

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the chipset does not lock the pci or agp bus, the pll does. The chipset just must have the ability to run the pci and agp asynchronous from the fsb. Chipsets from the socket 7 era could be modded to lock the pci bus with a 33.3mhz oscillator and hex inverter. The adoption of being able to use a pci lock came later and i would say that the first chipset that could run asynchronous agp was the i810, although some bx boards have been show to support asynchronous fsb/agp, mine unfortunatly did not :frown: (yes i tryed).

So realy it was the adoption of PLL's that supported locking buses which was not adopted quickly because they really didn't care much about overclockers. However i do find it odd that all this time refrence inputs for USB and FDD have been locked.


If it isn't a P6 then it isn't a procesor
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trox

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Oct 22, 2003
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ok, so maybe i'll settle to a pci divider of 40 just to be sure. but my question is this, what is the best configuration if you were to choose on this two options:

first option: 160/160/40. = 1.52 ghz
I have tried 6 hrs of prime95 and various games and proved to be stable. pls. take note that my memory is only pc133. Also tried hot cpu test pro for 6 hours and no errors or problems also.

2nd option: 163/122/40 = 1.548 mhz
Also tried this setting for a few hours and proved stable also. Same test programs were applied. This gives me more mhz but lower memory setting.

The above settings are the highest that my board can do with 40 pci divider. what is the best choice of the two? Thanks
 

pIII_Man

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without a doubt 160/160/40 runing your memory at 122mhz may even give you worse performance in some apps than running your cpu at stock speed.


If it isn't a P6 then it isn't a procesor
110% BX fanboy
 

pIII_Man

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if the system is stable don't worry about it...if its unstable then bring it back. But really if you are running it at stock voltage there is not much of a chance that you will kill it.


If it isn't a P6 then it isn't a procesor
110% BX fanboy