ohhh i realize i didn't put my contribution here.
i successfully upgraded 2 PS/2's with SXLC2 50 and 40 Mhz chip.
first is a model 35 (isa) originally with a SX20, successfully upgraded with the SXLC2 50 G50 (without 3,3v mod) , overclocked to 33 MHz. and for bonus, cache is enabled by bios.
and clock doubling work with software control, and 66 MHz is possible totally reliably. but i added a heatsink, clock doubling also mean heat doubling 😀.
second is a model 55SX (mca) originally SX16, successfully upgraded with the 40 Mhz (so real 5V part) , tried overclock to 20 MHz but fail. cache is enabled by bios.
clock doubling doesn't work, the machine crash. don't know why.
some pictures :
- model 35
- model 55SX