[rzzzt]

There were 8088 variants rated for 8+ MHz, motherboards supporting them had independent oscillators for the CPU and the ISA bus and you could switch speeds with software or a keyboard shortcut. Maybe also a button?

[steelframe]

I owned one. The combo was Ctrl-Alt-Minus.

There were a lot of DOS games that were designed to run at exactly 4.77Mhz. The gameplay and music would run at 2x if you enabled turbo mode.