overclocked agp, pci bus

[peter p]

I've read that when overclocking your cpu you overclock your pci, agp bus and your hard drives. What do you have to do to these to compensate for the overclock? Is there setings in the bios for this and what should they be set at?

[RainMaQer]

When you raise the FSB it raises the pci, agp, etc. buses aswell... this is because in order to get the pci buses... there is a divider that is applied to the FSB... at 100 MHz this divider is 1/3 for the pci and 2/3 for the agp... (1/3 of 100 is 33... the pci bus speed... 66 for the agp) The hard drives are on the same bus as the pci... if you can... look for dividers (NOT multiplier) in the bios OR if you can raise your FSB... look to see if it mentions another number next to it... at 100 the other number should be 33... or check your manual to see it theres a dip switch or jumper that controls it...

BTW... what mobo do you have :D

[peter p]

Originally posted by RainMaQer
When you raise the FSB it raises the pci, agp, etc. buses aswell... this is because in order to get the pci buses... there is a divider that is applied to the FSB... at 100 MHz this divider is 1/3 for the pci and 2/3 for the agp... (1/3 of 100 is 33... the pci bus speed... 66 for the agp) The hard drives are on the same bus as the pci... if you can... look for dividers (NOT multiplier) in the bios OR if you can raise your FSB... look to see if it mentions another number next to it... at 100 the other number should be 33... or check your manual to see it theres a dip switch or jumper that controls it...

BTW... what mobo do you have :D
I have a asus cusi-fx mobo. I don't see any dividers. The only thing next to my fsb is sdram eg. fsb/sdram 145/145. There is another setting that says "isa bus clock (PCICLK/4) This function allows you to set the isa bus clock frequency. PCICLK/4 sets your
ISA bus at a quarter speed of the pci bus." There is 2 settings, PCICLK or 7.159MHZ. does this mean anything?

[batboy]

Overclocking your PCI and AGP bus a little bit is a good thing as far as increasing performance, you just don't want to go too far out of spec or else you'll get instability. The other option is to try to settle for the next highest default FSB, so everything will be in spec. For example: if you have a 1 gig Celeron that is supposed to run at 100 MHz FSB, then set your goal for 133 MHz FSB (if your motherboard has 1/4 PCI dividers).

[peter p]

Originally posted by batboy
Overclocking your PCI and AGP bus a little bit is a good thing as far as increasing performance, you just don't want to go too far out of spec or else you'll get instability. The other option is to try to settle for the next highest default FSB, so everything will be in spec. For example: if you have a 1 gig Celeron that is supposed to run at 100 MHz FSB, then set your goal for 133 MHz FSB (if your motherboard has 1/4 PCI dividers).
I have a PIII 700 / 100. I have it over clocked to fsb/sdram 145/145 giving me 1015 MHZ. Seems to be okay, had it like this for over a year now.

[deez]

Nice OC on that 700 peter...at 133FSB your AGP generally drops to 1/2 divisor and your PCI to 1/4 so your not running very far out of spec on either one.