Hehehe that first picture is weird! It shows 9 cpu types and only 8 settings? 🤣

I would go with the second one as it is the only one that has jp8: 1-2, 7-8 and that is probably the 3x multi?

Also note that you have the mmx cpu (2,8v p55c) and that board only seems to support the p54c 3,3v versions?

You CAN run the mmx at 3,3v but please use a beefy cooler to compnsate for the extra heat generated by the extra volts. It is not recommended and at your own risk but in my experience it will not give any problems as long as you use a good cpu cooler.

BTW: The p100 settings is 1,5x66mhz. The 1,5 multi will work on a lot of p200mmx cpu's as 3,5x and will give you 233mhz. The later p200mmx ones are locked and will not work with the 1,5x=3,5x setting but it might be worth it to try if you want more speed. So if you want to try and see if it runs at 233mhz set it as a p100.

I have a hypothesis that might explain your trouble.

It seems that the multiplier is solely determined by JP8. Assume pins 1,3,5,7 are connected to CPU and 2,4,6,8 are connected to signal source (3.3V, ground, or float). If the pins are wired as follows, and your MMX chip is partially locked, you might face the frustration of totally locked multiplier:

BF0 <--> 1 2 <--> float
BF1 <--> 3 4 <--> 3.3V or float
BF0 <--> 5 6 <--> ground
BF1 <--> 7 8 <--> ground

Partially locked MMX will ignore the signal from BF1 pin and its BF0 pin will be pulled low when being float. Therefore no matter how you change the settings of JP8 the CPU can only receive ground signal from both BF0 and BF1, resulting in multiplier locked at 2.5x.

It's easy to check the wiring if you can get access to a multimeter.

Are you implying that he might have a 166 remarked as a 200?

I've purchased multiple CPUs trying to track this down... I purchased a 200MMX "plastic", a 200MMX ceramic, and a 166MMX "plastic.

Both the 200mhz CPUs seem to ignore the 3x multiplier.

Anonymous Coward wrote:

Are you implying that he might have a 166 remarked as a 200?

He might... But I think a partially locked MMX 200 would also behave like this.

Tyrantulas wrote:

I've purchased multiple CPUs trying to track this down... I purchased a 200MMX "plastic", a 200MMX ceramic, and a 166MMX "plastic.

Both the 200mhz CPUs seem to ignore the 3x multiplier.

Are they both not responding to other JP8 settings?
Do you have other boards to test the CPUs?