The correct way to wire them is so that turbo "on" means full speed and turbo "off" means slowed down. Different motherboards implemented it differently. Usuall

The correct way to wire them is so that turbo "on" means full speed and turbo "off" means slowed down. Different motherboards implemented it differently. Usually downclocking the FSB or inserting waitstates for memory access. They originated with "Turbo XT" class machines which ran an 8088 but at 8, 10 or 12 MHz -- faster than a real IBM PC/XT. Turbo on meant a faster machine, and turbo off meant 4.77 MHz -- fully compatible with timing-sensitive PC software. Later, in the 386/486 whitebox PC era, some machines had the buttons wired wrong and now it's a meme that turbo made the computer go slower, but that was never true for systems built correctly.