PCI and AGP speeds while overclocking..

[spacelord]

I have a Soyo Dragon Ultra P4X400 motherboard. There are no BIOS settings (that I can find) that allow one to set the multiplier for the PCI and AGP bus rates. This board can support 100 or 133 fsb... but can be overclocked.

Does the motherboard automatically select the best ratio to keep the PCI at 33Mhz? if I bump my fsb above 133 I assume my PCI and AGP bus rates are going to go up.

I can change the ratios for the memory.. but my problem may be keeping the PCI and AGP within good limits for a stable system.

thanks for any help.

 

[MadTom]

Well, this seems very strange - just downloaded and read the manual, but it's not mentioning the PCI/AGP dividers... However it seems that it is automatically in one range (100-132 MHz, AGP 2:3 and PCI 1:3 I guess; and 133-165 MHz, AGP 1:2 and PCI 1:4). Wasn't a big help, or?

 

[spacelord]

yeah, my manual which came with the MB and the "latest" pdf manual from Soyo mention nothing about PCI and AGP dividers.

I guess I couldn't have said it better, but what you wrote sounds like what I was thinking.

I will try and send an email to Soyo customer support, but am expecting a typical Soyo response of "Set your Bios back to defaults with the Jumper".

 

[fluxquantum]

according to this review

Soyo P4X400 Dragon Ultra socket 478 DDR400

Can't adjust the FSB/PCI/DDR/AGP ratios

 

[spacelord]

I don't think that statement is completely true, because I think I can adjust the memory ratio.

 

[Duvie]

Why is Via and Sis the only numnuts companies not to offer a agp/pci lock??? That is the real question...the second question is why did you buy it. I have heard nothing but bad ocing results and ddr problems with all of these non intel chipset mobos, yet ppl buy......


I would assume like with many of the sis and intel mobo it likely shifted to a 1/4 divider automatically at 133fsb and may or may not switsh to a 1/5 divider at 166fsb....So 150fsb for example will have a 1/4 divider and run the pci at 37.5mhz and agp at 75mhz.

Doesn't when you manually change the cpu frequency give a look like this (xxx/xx)...Ie like 133/33 or 150/38??? All 3 of my intel chipset mobos have and so did my sis645 chipset mobo.....

 

[spacelord]

 

[spacelord]

I have found nowhere in the BIOS which shows PCI or AGP speeds. I either do the math myself or check it once I boot.

apparently I overlooked the AGP/PCI features of the motherboard. I like it otherwise, but could ony recommend it to people who do not want to overclock.

I had my system easily overclocked to around 2.8GHZ (147 fsb * 19) , my memory was around 294MHZ (its 333mhz memory but had to fall back on a different memory multiplier) I would have gone higher except my PCI and AGP speeds kept going up too.

what are safe maximum PCI and AGP speeds?

thanks

 

[Egrimm]

Originally posted by: spacelord
what are safe maximum PCI and AGP speeds?

Nothing above specs (33Mhz) can ever be 100% safe, but a rule thumb is that 35Mhz pci/70agp is fine and anything under 37Mhz shouldn't give problems. When you get to 39-40Mhz most people start to get problems though. Problems is mostly due to the high pci-speed which causes problems with some cards and bad writes to hds, most gfx-cards can easily take high agp-speeds.
I've run an old Celeron333 @ 416 with 41.5pci and 83 agp for 3 years now and never had a single problem at all so it is possible to run without problems but I'd say I'm lucky compared to when other people start having problems.