In the 80s and 90s, some desktop PCs included a "Turbo" button, but what it actually did was a little unclear. What was it for and why don't PCs have them now?

Back in the 486 days, it was common to see a “Turbo” button on the front panel of many PCs, which was used to toggle between the CPU’s maximum speed and a slower clock rate that w… ...

Also, TURBO button. Serdashop has a device that does exactly that! The HDD Clicker operates off the HDD LED header on your motherboard, and it sounds sort of like a real hard drive.