It's motherboard dependant. Some stick the "FSB" synch with ISA, some knock it down to 4.77Mhz, some just turn off caches. It's kinda hard to tell what exactly happens without hooking it up to test equipment, as nothing on a 486 board is hooked into a SMB System Management Bus that can give that sort of info to utilities. All you can do is make guesses based on benchmarks. Possibly you can find an alternative lower multiplier setting like 2x and an alternative bus speed, like 20Mhz, or even maybe an undocumented 16Mhz, if you wanted to slow it down and really know where you were at.

Good answer BitWrangler !
It is board dependent AFAIK. One of my 486 boards drops to 8mhz ISA speed, another 486 board just sets clock divider to the minimum, another just shuts off the cache.
Sorry no good answer from me 😀

Ok, I thought that it would be possible to use a 120Mhz part and de-turbo it to like 60 Mhz.. Should be ideal for games that would run fine on a 66Mhz clocked cpu.
So after reading the second post, that wouldnt be possible..