System Unit

This post will detail several parts of a system unit including the interfaces on a motherboard.

Expansion Card

An expansion card is a printed circuit board (often abbreviated to 'PCB') that is attached to an expansion slot of the motherboard of a computer system for additional functionality. The contacts or edge connectors on the edge of the card are designed to fit specific slots such as Peripheral Component Interconnect (PCI) or PCI-Express slots. Below are several examples of expansion cards.

The ATI Radeon HD 5870 - currently the most powerful commercially available single graphics card in the world, built for PCI-E 2.0 x16 slots.

Source: http://www.modreactor.com/images/stories/news/2009/September/10/Radeon_HD_5870_03.jpg

The Creative Sound Blaster X-Fi Xtreme Audio sound card is built for PCI slots.
Source: http://asia.creative.com/products/product.asp?category=1&subcategory=873&product=15855&nav=2&listby=usage

Network Interface Card (NIC)

Network interface cards or network cards are a type of expansion card typically built for PCI slots to provide a system with the ability to connect to a network. Wireless network cards allow network connectivity wirelessly while Ethernet network cards allow a system to access a network via an Ethernet connection. Many modern motherboards usually provide an integrated network interface.

A PCI network card.

Source: http://gizmodo.com/assets/resources/2007/08/network_card2.jpg

Plug & Play

'Plug & play' describes the functionality of which new hardware devices are automatically detected and configured by and for a system and may typically be used without the manual installation of drivers. Plug & play devices may include the mouse, keyboard and monitor. This functionality is also common on USB devices.

CPU Sockets

A CPU socket or CPU slot refers to the component on a motherboard designed to house a microprocessor. They physically support the CPU, provide support for CPU heatsinks and other CPU coolers, forming an electrical interface between the microprocessor and the motherboard and allowing interchangeability of CPUs compatible with the slot.

An AM3 socket on an AMD motherboard for AMD Phenom II, Athlon II and Sempron processors.

Source: http://en.wikipedia.org/wiki/Socket_am3

Chips

A chip is a small integrated circuit manufactured on a thin wafer of semiconductor material. On a motherboard, a chipset refers to a group of integrated circuits that manages the transportation of data from various components by a bus. Typically, motherboards are identified by their chipsets, including what processors are compatible with them. For instance, an Intel X58 chipset motherboard will support Intel Core i7 CPUs. Chipsets may also support multi-GPU technology by graphics card manufacturers Nvidia and ATI (Scalable Link Interface or SLI and CrossFire respectively) if the motherboard has two AGP or two PCI-E x16 slots.

Slots

On a motherboard, slots are similar to sockets that allow for the connectivity of additional components or devices based on the type of slot. The ubiquitous Universal Serial Bus (USB) port is also considered a slot. Other types of slots include the now-obsolete Accelerated Graphics Port (AGP) slots and Peripheral Component Interconnect-Express (PCI-E) slots.

An old AGP slot, circled in yellow.

Source: http://www.tips4pc.com/images/agp_slot.jpg

Bus Lines

In computer architecture, a bus is a subsystem that transfers data between components inside or between computers. Buses may be parallel wires which carry data parallel across multiple wires or in serial form where data is transferred one bit at a time. The bus bandwidth determines the amount of data that can be transferred at once. The bit rate of the bus is dependent on the type of the bus.

Serial Port

A serial port is a physical interface that allows the transfer of data one bit at a time. Data transfer through such ports connects a computer to terminals and peripherals. In modern computers, serial ports are mostly obsolete, being replaced with USB and FireWire, but are still used in certain industrial products and shop till systems.

A male DE-9 connector used for a serial port on a IBM PC compatible computer.

Source: http://en.wikipedia.org/wiki/Serial_port

Parallel Port

Also known as a printer port or Centronics port, a parallel part is similar to a serial port, but data is transferred via parallel communication instead, where several data signals are sent simultaneously over several parallel channels.

A DB-25 parallel printer port, as on IBM-PC style, and a few other types of computers.

Source: http://en.wikipedia.org/wiki/Parallel_port

Universal Serial Bus

The basic USB trident logo; each released variant has a specific logo variant.

Source: http://en.wikipedia.org/wiki/USB

Universal serial bus (often abbreviated to 'USB') is an external bus standard intended to replace most serial and parallel ports. USB is typically used to connect various computer peripherals such as mice, keyboards, gaming controllers, digital cameras and external storage devices.

FireWire Port

Illustrations of various forms of IEE 1394 ports.

Source: http://doctormo.files.wordpress.com/2009/07/firewire-ports.png?w=450&h=230

A FireWire port is a physical interface using the IEEE 1394 interface as a serial bus interface standard for high-speed data transfer and is commonly used in computers for digital video, digital audio, automotive and aeronautics applications. Most digital camcorders support IEEE 1394 connectivity to transfer footage to a system. The second amendment of the FireWire interface, FireWire 800 (IEEE 1394b) has been proven to be substantially faster than Hi-Speed USB. It must be noted that 'FireWire' is Apple's brand name for the interface while Sony refers to it as i.LINK.