question about agp/pci bus lock

[jonn]

My motherboad doesnt support agp/pci bus lock, so raising my Bartons bus speed raises the agp/pci bus as well, is there any "safe" limit on how high you can let the agp/pci bus raise without causing any problems? and if so, would you know how the problems would manifest themselves? thanks

 

[jonn]

Know one knows?

 

[MichaelD]

Hi John,

The honest, correct answer is "try it and see." Seriously! W/O an AGP/PCI lock, raising your FSB also raises those bus speeds from their specified 66 and 33MHz, respectively.

"How far" you can go depends on component sensitivity. For example, your soundcard MIGHT NOT care if it's bus is at 38MHz, but your NIC may crash and die at 38 or even 35MHz.

Hard drives as well are affected by raising bus speed. Data loss or HD DAMAGE is possible. Maybe not probable, but the risk is there.

This is why everyone loves the NForce2 chipset (at least for AMD CPUs!). That built-in lock is simply God's gift to Geeks.

The "signs" might be there and they might not be, unfortunately. Something as simple as the soundcard not working/being detect is a good one. The system not booting is a very obvious one.

Hope this helps.

 

[jonn]

thanks, so being fairly new to OC'ing. What exactly "raises" when the buss speed goes up? is it voltage, transfer speed, or whatever you call it.?
yes i know the lock is on some motherboads, wish i knew that before i bought the gigabyte.

I dont know what is crapping out on mine when i raise the cpu buss. probably the 2700 memory. I can get a barton 2500 up from 1836 to about 1940 before comp. freezes. So i backed it down till it didnt freeze, then a tad more. Cant change muilitpliers either with this board/cpu. Oh well...

 

[MichaelD]

PC2700 memory is rated at 166MHz, which is what you're Barton's default FSB is (333MHz=166x2 (DDR)).

Good PC2700 might be able to make it to 180 or even a little higher depending on many factors.

The motherboards' chipset is designed to keep everything in sync. I.E. at 166MHz, the PCI is at 33MHz and the AGP at 66MHz.

I forget the exact ratio, but when you raise from 166 to say, 175, the PCI goes up to 36MHz and the AGP to 70MHz (not exact numbers, just giving you an example)

Hope this helps.

 

[jonn]

Thanks for the replys, i know what the bus numbers are, and how they raise in relation to raising the cpu bus, what i was really asking is, if i can say it correctly, :what is bus speed:
i mean is it the bus voltage, how much data it is allowed to send, etc..???? just trying to understand all aspects of these PIA things

 

[Haden]

You can say it's frequency, how often signal is send. 1Hz - once per second.

 

[jonn]

Hmmm, well off the top of myr head that sounds like it wouldnt really hurt the cards in the agp/pci slots, sounds like if you go to far it will just give you errors or lockups? is that what i should be assuming? mine are pci=35 and agp=68 what ya think?
i have no problems at all with them there for last couple of days. All seems well. Its just hard to find out, it seems exactly if raising to high would damage anything, or just give errors and lockups, or to find a "ball park" idea of the safe limits.
"i think ill stick to rebuilding engines, much easier"

 

[jonn]

Hmmm, well off the top of myr head that sounds like it wouldnt really hurt the cards in the agp/pci slots, sounds like if you go to far it will just give you errors or lockups? is that what i should be assuming? mine are pci=35 and agp=68 what ya think?
i have no problems at all with them there for last couple of days. All seems well. Its just hard to find out, it seems exactly if raising to high would damage anything, or just give errors and lockups, or to find a "ball park" idea of the safe limits.
"i think ill stick to rebuilding engines, much easier"

 

[Haden]

Should be ok, I've been running XP 1500+ overclocked with PCI at 37Mhz w/o any troubles for about a year.
Just pay big attention to crashes if any occur, things to watch out include:
nic problems (like slow performance) - especially true with older 100mbps 3Coms
sound problems (noise, pops etc.)
hdd data corruption.