Parts of Computer System Unit

Power Supply - A modern computer power supply is a switched-mode supply designed to convert 110-240 V AC power from the mains supply, to several output both positive (and historically negative) DC voltages in the range 12V to 3.3V. The first computer power supplies were linear devices, but as cost became a driving factor, and weight became important, switched mode supplies are almost universal.

The diverse collection of output voltages also have widely varying current draw requirements, which are difficult to all be supplied from the same switched-mode source. Consequently most modern computer power supplies actually consist of several different switched mode supplies, each producing just one voltage component and each able to vary its output based on component power requirements, and all are linked together to shut down as a group in the event of a fault condition.

The most common modern computer power supplies are built to conform to the ATX form factor. The power rating of a PC power supply is not officially certified and is self-claimed by each manufacturer. A common way to reach the power figure for PC PSUs is by adding the power available on each rail, which will not give a true power figure. The more reputable makers advertise "True Wattage Rated" to give consumers the idea that they can trust the power advertised.





Motherboard - The motherboard is the main circuit board of a microcomputer. It is also known as the mainboard or system board, or, on Apple computers, the logic board. It is also sometimes casually shortened to mobo.



Central Processing Unit (CPU) - It is the central electronic chip that determines the processing power of the computer, machine that can execute computer programs.



CD ROM or DVD drive - CD-ROM discs are read using CD-ROM drives, which are now almost universal on personal computers. A CD-ROM drive may be connected to the computer via an IDE (ATA), SCSI, S-ATA, Firewire, or USB interface or a proprietary interface, such as the Panasonic CD interface. Virtually all modern CD-ROM drives can also play audio CDs as well as Video CDs and other data standards when used in conjunction with the right software. Today the most common use is DVD Drive same dimensions as compact discs (CDs) but store more than six times as much data.

Variations of the term DVD often describe the way data is stored on the discs: DVD-ROM has data that can only be read and not written, DVD-R and DVD+R can record data only once and then function as a DVD-ROM. DVD-RW, DVD+RW and DVD-RAM can both record and erase data multiple times. The wavelength used by standard DVD lasers is 650 nm, and thus the light has a red color.



Fan - A computer fan can be any fan inside a computer case used for cooling purposes, and may refer to fans that draw cooler air into the case from the outside, expel warm air from inside, or move air across a heatsink to cool a particular component. The use of fans and/or other hardware to cool a computer is sometimes referred to as active cooling.



Hard Drive - Mass storage devices store programs and data even when the power is off; they do require power to perform read and write functions during usage. Although semiconductor flash memory has dropped in cost, the prevailing form of mass storage in personal computers is still the electromechanical hard disk.

The disk drives use a sealed head/disk assembly (HDA) which was first introduced by IBM's "Winchester" disk system. The use of a sealed assembly allowed the use of positive air pressure to drive out particles from the surface of the disk, which improves reliability.

If the mass storage controller provides for expandability, a PC may also be upgraded by the addition of extra hard disk or optical disc drives. For example, DVD-ROMs, CD-ROMs, and various optical disc recorders may all be added by the user to certain PCs. Standard internal storage device interfaces are ATA, Serial ATA, SCSI, and CF+ type II in 2005.



Heat Sink - Is an environment or object that absorbs and dissipates heat from another object using thermal contact (either direct or radiant). Heat sinks are used in a wide range of applications wherever efficient heat dissipation is required; major examples include refrigeration, heat engines, cooling electronic devices and lasers.



Video Card - Also known as a graphics accelerator card, display adapter, or graphics card, is a hardware component whose function is to generate and output images to a display. It operates on similar principles as a sound card or other peripheral devices.

The term is usually used to refer to a separate, dedicated expansion card that is plugged into a slot on the computer's motherboard, as opposed to a graphics controller integrated into the motherboard chipset. An integrated graphics controller may be referred to as an "integrated graphics processor" (IGP).

Some video cards offer added functions, such as video capture, TV tuner adapter, MPEG-2 and MPEG-4 decoding, FireWire, light pen,TV output, or the ability to connect multiple monitors.



Floppy Drive - Is a data storage medium that is composed of a disk of thin, flexible ("floppy") magnetic storage medium encased in a square or rectangular plastic shell. Floppy disks are read and written by a floppy disk drive or FDD, the initials of which should not be confused with "fixed disk drive," which is another term for a (nonremovable type of) hard disk drive. Invented by IBM, floppy disks in 8-inch (200 mm), 5¼-inch (133⅓ mm), and the newest and most common 3½-inch (90 mm) formats enjoyed many years as a popular and ubiquitous form of data storage and exchange, from the mid-1970s to the late 1990s. While floppy disk drives still have some limited uses, especially with legacy industrial computer equipment, they have now been largely superseded by USB flash drives, CD-ROMs and DVD-ROMs.



Modem - Is a stripped-down that replaces tasks traditionally handled in hardware with software. In this case the modem is a simple digital signal processor designed to create sounds, or voltage variations, on the telephone line. Softmodems are cheaper than traditional modems, since they have fewer hardware components. One downside is that the software generating the modem tones is not simple, and the performance of the computer as a whole often suffers when it is being used. For online gaming this can be a real concern. Another problem is lack of portability such that other OSes (such as Linux) may not have an equivalent driver to operate the modem. A Winmodem might not work with a later version of Microsoft Windows, if its driver turns out to be incompatible with that later version of the operating system.



Zip Drive - Is a medium-capacity removable disk storage system, introduced by Iomega in late 1994. Originally, Zip disks had a capacity of 100 MB, but later versions increased this to first 250 MB and then 750 MB.

The format became the most popular of the super-floppy type products but never reached the status of a quasi-standard to replace the 3.5-inch floppy disk. Later, rewritable CDs and rewritable DVDs largely replaced Zip drives, and the internal and external CD writers known as Zip-650 or Zip-CD were sold under the Zip brand.



Sound Card - A sound card (also known as an audio card) is a computer expansion card that facilitates the input and output of audio signals to/from a computer under control of computer programs. Typical uses of sound cards include providing the audio component for multimedia applications such as music composition, editing video or audio, presentation/education, and entertainment (games). Many computers have sound capabilities built in, while others require additional expansion cards to provide for audio capability.



Ribbon Cable - A ribbon cable (also known as multi-wire planar cable) is a cable with many conducting wires running parallel to each other on the same flat plane. As a result the cable is wide and flat. Its name comes from the resemblance of the cable to a piece of ribbon (which is likewise wide and flat).

Ribbon cables are commonly seen for internal peripherals in computers, such as hard drives, CD drives and floppy drives. On some older computer systems (such as the BBC Micro) they were commonly used for external connections as well. Unfortunately the ribbon-like shape makes them awkward to handle, especially when there are a lot of them, and so round cables have almost entirely replaced ribbon cables for external connections.