A while ago I've been told that some generic-brand PC, (yet packed on an IBM5150 case) had the ability to become a 80386 upon pressing Ctrl-Alt-Del (warm reboot) ?
I guess there might have been (for sure) another processor in them but I've been unable to find details online about these mid-80's beasts.
EDIT
Some information about a similar concept in a September '86 magazine
Some Linux stuff about Ctrl+Alt+KP+
But as far as I remember it was Ctrl+Alt+Del and there was no turbo button on the machine.
A guess is that it's what we used to call IBM PC and compatibles back in the time (a clone) :)