It is a distant memory and I might well be wrong, but I think this board has a turbo function that messes slightly with the clock speed, maybe the turbo function needs to be enabled / disabled. Just a guess though I did have this board a long while ago and think I remember something odd about the turbo function!

All FSBs below 105 MHz require the FS3 pin of the clock generator chip to be high: https://theretroweb.com/chip/documentation/ic … 2c329209335.pdf

Can you set an FSB of 110?

If none of the lower FSBs work, it would indicate that the FS3 pin is stuck low or that the clock generator chip is damaged. Is there an additional pull-up resistor at the FS3 pin? Test if it has gone bad. With the board on and the FSB set to 100, is the FS3 pin high?

asdf53 wrote on 2026-06-27, 17:58:

All FSBs below 105 MHz require the FS3 pin of the clock generator chip to be high: https://theretroweb.com/chip/documentation/ic […]
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All FSBs below 105 MHz require the FS3 pin of the clock generator chip to be high: https://theretroweb.com/chip/documentation/ic … 2c329209335.pdf

Can you set an FSB of 110?

If none of the lower FSBs work, it would indicate that the FS3 pin is stuck low or that the clock generator chip is damaged. Is there an additional pull-up resistor at the FS3 pin? Test if it has gone bad. With the board on and the FSB set to 100, is the FS3 pin high?

Yes I can set 110. Also when I set 95 I get 110. Where is this FS3 pin?

Forevermore wrote on 2026-06-27, 22:38:

Where is this FS3 pin?

On the first page of the PDF I linked above, there's a diagram of the pin configuration. Pin 1 is marked with a little dot or indentation, pin 2 is FS3.

asdf53 wrote on 2026-06-28, 03:09:

Forevermore wrote on 2026-06-27, 22:38:

Where is this FS3 pin?

On the first page of the PDF I linked above, there's a diagram of the pin configuration. Pin 1 is marked with a little dot or indentation, pin 2 is FS3.

I'm sorry I don't have the ability to test right now. But I think it's fair to infer the clock gen is faulty. I initially was hoping it was some quirk of this particular motherboard I wasn't familiar with. I've encountered similar things on a S370 board I have.

Thanks for that documentation though, that will help in future 😀

I remember another user posting about a faulty clock generator on the same motherboard (older revision, though): Re: Pentium MMX 233 Reporting as 290MHz

And that he fixed it by injecting more current into the frequency select pins. That would indicate that there is some type of leakage / short circuit inside the clock generator that's draining away the logic high signal. You could test this by temporarily adding a smaller resistor on top of the pull-up resistor near the FS3 pin (it might work to hold a through-hole resistor onto the pads to bypass the SMD resistor and with your other hand, power on the board and see what happens).