First post, by sofakng
The IBM PC 330/350 models offered CPUs up to Pentium MMX 233 but they excluded the 2.8v VRM module unless it came with an MMX CPU. However, the pin headers are still present on the motherboard and the BIOS supports it without any issues.
The VRM module appears to be a simple 30-pin adapter with a 5-pin voltage regulator and a few resistors/capacitors:
I've compared the Semtech datasheet and used a multimeter to diagram the pins on the IBM motherboard:
This is about as far as I can go myself so I'm hoping somebody with more knowledge can help out?
If somebody could help me with the VRM circuit I should be able to design and order some PCBs and distribute them to everybody interested.
Thanks so much for any help!