http://pdf1.alldatasheet.com/datasheet-pdf/vi … +/datasheet.pdf
missing R149 at Pin 16 of ICS9148-60 is most likely a 200ohm pullup to 3.3V

cheapest way of gimping BX board to 66MHz speeds

AlessandroB wrote:

the only thing I have to do is weld a 10kohm smd resistor in that place?

more likely 0 or 200ohm, but first get a multimeter, set it to resistance mode and measure (on turned off computer) ICS9148-60 between
-pin 16 (our magic select signal) and pin 19 (ground)
-pin 16 (our magic select signal) and 20 (3.3V source)
-other leg of R149 and pin 19 (ground)
-other leg of R149 and 20 (3.3V source)

This will tell us what needs to be modified. This board will definitely run 100MHz, IBM simply limited cheaper version by omitting some parts.

If that's how an internal voltage divider looks like on a 100MHz FSB PII, then it's pretty self explanatory, why this motherboard can't run @ 100MHz FSB. Klamath PII BSEL is always tied to ground, hence only 66MHz FSB, while Deschutes allows 100MHz FSB only when PLL has a pull-up resistor on MB.

First of all thank you, you are all extremely professional but I see that it is something a little complex to do, for the moment my work leaves me very little time so I pause and try in August. For now I will use the 66mhz computer. As soon as I can try it I will continue this post. thanks for now.

AlessandroB wrote on 2019-05-24, 07:46:

First of all thank you, you are all extremely professional but I see that it is something a little complex to do, for the moment my work leaves me very little time so I pause and try in August. For now I will use the 66mhz computer. As soon as I can try it I will continue this post. thanks for now.

Did you have any luck making a 100Mhz bus CPU (be it PII or PIII) work properly in this system?
I have recently acquired the same one (300GL 6287) and faced the same problem.

Installed latest BIOS rom available but nothing...all 100mhz bus Pentium II and Pentium III tried, work at 66mhz.

Why would they install DIP switches on the board and a sticker indicating how to enable 100mhz bus , if it doesn´t work at all, is beyond my comprenhension...

Because that way they could sell 100 MHz capable models for more 😀

Paadam wrote on 2022-01-17, 15:49:

Because that way they could sell 100 MHz capable models for more 😀

I can understand that, but at least...do not install the Dip switches and paste misleading stickers on the system that is NOT 100Mhz capable...

Hello, same thing to me. I got an IMB 300GL (6287) with the stock Celeron 366Mhz. I updated the BIOS to the latest version (NHJT37A). Chipset is a i440BX aswell.

There is nothing in the motherboard, no jumpers, no switches.....etc.....there is NO way to change the FSB or the CPU multiplier. Every CPU i tried is read as "Pentium II 233mhz"...that's it.

But after all..... i mean, that's the machine and was born that way. The Celeron 366Mhz is not too bad for retrogaming paired with a Voodoo 1 / 2.