You will not find many external fan controllers for your desktop computers specially the ones having intuitive touchscreen interface. The one shown below is a new product by NZXT, the Sentry LXE touchscreen fan speed controller for desktop computers.
The NZXT Sentry LXE touchscreen external fan controller is aimed for computers that are meant to be gaming PCs that really get cooking during continuous game play putting more load on hard drives, processors, graphics chipset/card etc. The NZXT Sentry LXE external fan control includes a PCI card that easily slides in standard PCI slots and from there you can interconnect the temperature probes and fans. This external fan speed controller supports up to five fans.
A single cable connects the PCI card to the external touchscreen display. The NZXT Sentry LXE touchscreen display will indicate current temperatures and fan speeds which you can alter manually and either increase or decrease individual fan speeds. This desktop PC external fan controller will also indicate current time and date plus you also have to option to turn ON/OFF the display. Other features include alarm on user defined temperature settings.