I have a mobile MIIv 333, boot stable with 350 MHz and stock 2.2V VCore, needs more testing if Prime also runs stable. 300Mhz runs completely stable with the stock 2.2V VCore.

Here is a thread about it:
Re: Rarest CPUs?
Re: Rarest CPUs?

This should be a nice IBM CPU for a rare Super Socket 7 build. MII 433 speed for free, maybe also MII 500!

Some good threads on Cyrix:

Cyrix/ST/IBM Aiming for the stars!
Cyrix appreciation thread

My own rather boring thread on my MII:
Cyrix MII build

mwdmeyer wrote on 2022-11-09, 22:56:

Yeah even a K6-2 300MHz running on a 66MHz FSB should beat a Pentium 233 MMX in most things.

Handily even! I've compared my 233 to a K6-2 333 and the difference is quite noticeable.