This almost certainly qualifies as overkill, but it's still one of the best-looking fan controllers available. The NZXT Sentry LXE external fan controller lets you monitor your computer's temperature and adjust the various fan speeds with a color, touch-sensitive LCD display. The controller connects to an included PCI-E board, which adjusts up to 5 fans and measures temperatures from up to 5 temperatures at once. While it uses up a PCI-E slot, it doesn't take up the usual 5.25-inch device bay most hardware fan controllers occupy. At $60, it's an affordable, if overbuilt, way to make sure your custom-built, hyper-tweaked computer stays at the appropriate temperature.