'90s PC Case Gets Authentic Faux Turbo Clock Speed Gauge

Did you know that the thermostat on the wall of your office probably doesn't do anything? Some reports indicate that as many as 90% of employee-accessible thermostats exist purely as placebos. The idea is that the act of adjusting the thermostat will make you feel better, but it won't add to the company's energy bill. Elevator "close doors" buttons aren't often functional either, but pushing them makes you feel like you're achieving something. The infamous turbo clock speed gauges of the 1990s worked under a similar principle and Joshua Woehlke made his own.

The late '80s and early '90s saw a dramatic jump in computer processor clock speeds, which unearthed a pretty substantial problem. Prior to that, the focus was usually on increasing a computer's memory and that worked just fine. But clock speed increases caused software and games to run unpredictably, because developers often coded things like movement to be timed by the execution speed. So doubling the clock speed might make a video game character run twice as fast. To keep that software running properly, many computers of the '90s included a "turbo" button that would tell the processor to switch between its native speed and some slower speed suitable for that old software.

But users wouldn't always notice that speed difference and couldn't be sure that their turbo buttons were working. So manufacturers began including gauges that displayed the current clock speed. But like your office's thermostat, those weren't functional. They didn't show the actual clock speed. Instead, the readout would just switch between two predetermined numbers. In the name of authenticity, Woehlke replicated a faux turbo gauge like that for his vintage ATX PC case.

Like the gauges of the '90s, this doesn't need to know the processor clock speed; it just needs to know if the turbo function is active. This particular ATX case has a status light for the turbo function, so Woehlke chose to use an Arduino Mega board to monitor the state of that LED. The Mega is overkill for this project, but Woehlke had it laying around. The Arduino controls a small OLED screen that shows one of two preset clock speeds depending on the state of the LED. And as a final homage to retrocomputing, that OLED switches to a starfield screensaver 10 seconds after the user pushes the turbo button.