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[Help wanted] to make changes to the PCI frequency division for SIS496/497 and IMI SC464

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First post, by zwrr

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Hello everyone, I have a BEK-P407 motherboard, based on SIS 496/497 chipset, using IMI SC464 clock chip, the motherboard works very stably and the compatibility is very good, especially it has a 4V processor voltage, which can help POD83 overclock to 100 smoothly.

But there is a problem that confuses me, when the motherboard sets the bus frequency to 40Mhz, the PCI frequency is 1/2, which is 20Mhz, I checked the manual of the SC464 and SIS chipset, and tried all the exposed and undisclosed jumper settings on the motherboard, but it can't solve this problem.

I have measured the IMI SC464 pins, frequency jumpers, PCI clock pins and hope someone can help,
1.Is PCI frequency division done inside IMI SC464 and what controls it?
2. What hardware modifications can I make to fix the PCI bus frequency issue?

The attachment SC464.jpg is no longer available
The attachment Jumper.jpg is no longer available
The attachment IMI SC464 Manual.pdf is no longer available
The attachment SIS 496-497 Manual.pdf is no longer available
The attachment BEK-P407 Manual.pdf is no longer available

SBC1: Cyrix 5x86-120, HS-5x86HVGA, 16MB EDO, GD54M30, SB Pro II, HardMPU-wt
SBC2: VIA C3-800, PCISA-C800, 128MB SDRAM, Savage4 Pro, SB AWE64 Gold
SBC3: Tualatin-S 1.4G, PCI-6872, 256MB SDRAM, FX5200 PCI, Voodoo2 SLI, SB Live

Reply 1 of 2, by bertrammatrix

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I had a quick look at the manual - I'm pretty sure it is JP8 . It has a position for up to or over 33mhz. Set it the other way and see if pci is at 40.

Reply 2 of 2, by Horun

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zwrr wrote on 2024-10-16, 02:42:

Hello everyone, I have a BEK-P407 motherboard, based on SIS 496/497 chipset, using IMI SC464 clock chip, the motherboard works very stably and the compatibility is very good, especially it has a 4V processor voltage, which can help POD83 overclock to 100 smoothly.

Why is your board picture missing so many parts ? All those are populated on the two pictures at TRW...

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

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