My first PC was a 486DX/50 and until today I was totally unaware of the potential bus timing issues but I can not remember ever having had issues. But this might finally explain why it came with a turbo button - even though it should probably be called an anti-turbo button - that allowed changing the clock to 10 MHz. But now I wonder why they would have made it that slow instead of say 25 MHz or 33 MHz? I vaguely remember using the slower clock to make games playable that were running way to fast, so maybe that also factored into it.
The Turbo button did exist on processors that ran over 4.77 MHz of the original 8086. I had a Turbo button on the 9.54 MHz 8088, also on the 386 DX/40 (lowering the frequency to 8 MHz IIRC), it was not specific to 486. Actually the 486 was the last CPU that had that button, I think.
