What do you mean "the bios does not list"?

What happens if you install the CPU anyway?

Consider in general that the Winchip C6 CPU is much newer than the motherboards it is most suited for (single-voltage early So7 and So5 boards like this). Unless the motherboard vendor has kept up BIOS support for a long time, it won't know about the C6. Fortunately that should rarely be an issue. It will generally just work. Only BIOS that work with CPU whitelist (many OEM boards) will be a problem.

Any. It works with vanilla 430FX boards and identified as 486 CPU.

Using FPM, async cache.

Async cache won't harm or help it, because C6 has large L1 cache and don't rely on L2 much.

Well, that is good to know and I'll try once I have all the materials dragged out of closet and time to play with. I'll try the pentium 133 as baseline first then the C6.
Does SiS 5511, 12 and 13 chipset support memory interleave using four modules? I have two 8mb memory modules installed at this moment.

The board now has 512K async cache installed.

Cheers,