Clock divider software?

[technoid]

Did anyone ever come out with a CPU/bus clock divider program that can mess around with the chipset overriding the BIOS so as to change bus clock ratios?

I am currently upgrading an "old" (late 1990's) Pentium socket 7 motherboard, an ABIT AX5, specifically. Fastest FSB in BIOS is 83 MHz. There are no clock divider features in its BIOS. I would love to increase CPU freq to 83 (from 66), however, doing so can risk the PCI clock, because it would be at 41.5 (half of 83) instead of the normal 33 MHz. I already tried this and one of my hard drives got messed up. I have read that some peripherals cannot handle that high of a PCI speed. I also had to change the soundcard, because the current one kept locking up due to 83.

At 83 FSB, the divider to keep PCI stable would have to be something divisible by 2.5 if there ever was such a thing. Dividing by 3 would underclock the PCI and of course dividing by 2 would still overclock it to 41.5 as I said above.

I've looked at programs like SetFSB, SoftFSB, WPCredit, etc, but I am not really seeing anything in there about changing FSB to affect PCI and such unless I haven't looked close enough.

For now, I have been keeping the FSB to 75 instead, which ideally keeps the PCI (and ISA) clocks within normal range. CPU is an AMD K6-2 550MHz. So at 75 FSB and a CPU multiplier of x6, I would get 450MHz. But it would be nice to use 83 FSB so I could get 500MHz on the CPU without de-stabilizing everything else. Last resort would probably be to find a 3rd party BIOS maker. Otherwise keep FSB at 75, if nothing else.

Oh yeah, Windows 98SE compatibility would be nice too.

[TmEE]

Such division/ratio things need to be supported by the hardware, and I doubt that is the case or the BIOS would list such already.

[osRe]

In old mobos you set the ratios with jumpers.

[jumper]

technoid,

If any of the FSB tweaking tools you mentioned supports your mobo/clock chip, then boot at 83 with a divisor of 3 and then up the FSB to 90 for a PCI bus at 30 and CPU at 540.

If that works and you have a good heatsink, maybe you can overclock:

* FSB : 95 , PCI: 31.6, CPU: 570

* FSB: 100, PCI: 33.3, CPU: 600

Another possibility is to stabilize the PCI bus at 41.5 by disabling some of the PCI speed-up features (PCI burst, etc.) in BIOS.