Controller cards are installed on a motherboard to connect and control other PC components that include hard drives, disk drives, and input devices. Every component of hardware in your computer requires a controller for it to function. Some add-on components require that you install a separate controller card for effective function. For example, there are several types of hard drives. Adding a hard drive that is different from the original drive on your computer will require a controller card. Unlike older PCs, modern computers have controller cards pre-installed on the motherboard as part of the chipset. Controller cards are designed to connect to a PC's motherboard through the peripheral component connect (PCI) slot.
