recently i got another Socket 7 mobo from my scrap yard. it is weird PcChips M572 with jumperless feature.

and it didn't work. AMI bios post code for 166 CPU is 27, and for 166MMX cpu is 2A, which is undocumented.
Vcore in both cases 3.1v. so it is a "jumperless feature" issue.

i tried to flash an Award bios from another mobos with same chipset. And it did start at 120Mhz cpu clock and 3.1v core voltage.
But it has some issues to boot anyway. so i have to use original AMI bios.

i traced a "jumperless feature" and it's controlled by the "CPU - >(1) transistor keys - > (2,3) logic chips (one under the bios chip), and all components seems to be fine.

btw my mobo does not have chip no 4.

So i looking for a boardview, any schematics or datasheet for this crappy board.

Or maybe a good advice.