- 7 segment displays look cool and hypnotic as hell on whats otherwise a boring metal rectangle
- you can display your frames per second and other gamer(tm) stats
- computer
having actually built PCs with these cases in the past, they have a dirty secret: they do not actually show the current clock speed. they can be set to show two different arbitrary numbers, typically chosen with jumpers on the display itself, and they show one or the other number depending on the current status of the turbo switch
if the turbo switch is not connected to the motherboard, the display will still switch between the two numbers when you push the turbo button, even though nothing is happening to the state of the CPU. one of my friends had one of these AT cases that originally had a "turbo" capable board + CPU in it, but was eventually upgraded to a Pentium-something-or-other that had no turbo switch on the motherboard because that wasn't something you saw anymore, so he just set the jumpers on the panel to show the normal clock speed (100Mhz IIRC), but "666" if you pressed the turbo switch
theoretically you could instead display something other than numbers, if the characters are legible on seven-segment displays, because you're not entering in a number with the jumpers, but telling the display what segments to turn on or off in each mode. there's not a lot of letters that are displayable like that, but "LOL" would work, so you could set the display to be completely off in normal mode and make your PC laugh out loud when you press the turbo button
