Right - raising FSB means that not only is your RAM OC'd, but often your PCI bus (and everything on it) is moving faster, too.
Many MB's allow you to "lock" your PCI bus speed at a lower level. This allows an extreme OC to go further than the limit you might reach by trying to push a device on the PCI bus faster than it will go (for instance, a sound or network card that won't tolerate too high a speed and won't benefit from a higher speed anyway).
The big bonus in FSB OC'ing is in RAM - on my old Asus board (normally 100 FSB/133 memory) I can run it very stable at 110. Not only does my old Athlon 850 run at 935, the memory goes from 133 to 146 MHz. I can push the multiplier instead, but then I just get a CPU boost - the RAM remains at 133.
there is also the issue of P4s, they have locked multipliers. This makes multiplier changing impossible. The extra bandwidth that is gained from FSB overclocking makes up for the shear clockrate that can be had by bumping up the multiplier in many cases
as far as i know it either has an option or it doesn't. being an abit board, i would be very surprised if this was done through an onboard header, so into the bios you go!
yes, it's an abit board, but sorry csimon, so far as i know there is no locked PCI/AGP option, looked for a while for it, but you know that crazy VIA chipset loves dividers for PCI+AGP busses
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Mt_GoatHead Cheezy KnobPflugerville (north of Austin)Icrontian
edited October 2003
csimon said how would I lock my pci and agp bus on a kr7a-r?
This board is based on the VIA KT266A chipset and does not have any provision for locking the AGP/PCI buses. It does however allow you to select different divider ratios like [3:2:1], [4:2:1], [5:2:1], [6:2:1]. This is related as such; FSB:AGP:PCI. This helps to some degree but is not the same as a "Locked" AGP/PCI bus. Currently no VIA chipsets offer this and it is only available on NForce2 chipset boards. On some like on my Abit NF7-S the AGP/PCI bus is locked but I can increase the AGP bus for the purpose of squeezing more of an overclock out of my video card or finding its sweet spot.
well I'm more and more leaning towards an nv chipset rather than via for my next system anyway...
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Geeky1University of the Pacific (Stockton, CA, USA)
edited October 2003
You can't lock the pci/agp on ANY via chipset afaik. Certainly not any of the Athlon chipsets anyhow.
The basic reason you raise the FSB as much as possible is the same reason why video cards keep getting faster RAM- more memory bandwidth. a 2GHz CPU with a 100MHz FSB and a 20x multi is not going to be as fast as a 2GHz CPU with a 200MHz FSB and a 10x multi. You want as much memory bandwidth as possible, and the only way to do that is to raise the RAM/FSB speed.
Comments
however with the nforce2 boards most ppl just lock the pci and agp bus to attain a more better oc
Many MB's allow you to "lock" your PCI bus speed at a lower level. This allows an extreme OC to go further than the limit you might reach by trying to push a device on the PCI bus faster than it will go (for instance, a sound or network card that won't tolerate too high a speed and won't benefit from a higher speed anyway).
The big bonus in FSB OC'ing is in RAM - on my old Asus board (normally 100 FSB/133 memory) I can run it very stable at 110. Not only does my old Athlon 850 run at 935, the memory goes from 133 to 146 MHz. I can push the multiplier instead, but then I just get a CPU boost - the RAM remains at 133.
NS
(that IS an abit board right?)
The basic reason you raise the FSB as much as possible is the same reason why video cards keep getting faster RAM- more memory bandwidth. a 2GHz CPU with a 100MHz FSB and a 20x multi is not going to be as fast as a 2GHz CPU with a 200MHz FSB and a 10x multi. You want as much memory bandwidth as possible, and the only way to do that is to raise the RAM/FSB speed.