Antes

Computer components
A computer case (also known as a computer chassis, cabinet, box, tower, enclosure, housing, system unit or simply case) is the enclosure that contains most of the components of a computer (usually excluding the display, keyboard and mouse). A computer case is sometimes incorrectly referred to eponymously as a CPU referring to a component housed within the case. CPU was acommon term in the earlier days of home computers, when peripherals other than the motherboard were usually housed in their own separate cases.
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Power supply
Main article: Power supply unit (computer)
A power supply unit (PSU) converts alternating current (AC) electric power to low-voltage DC power for the internal components of the computer. Somepower supplies have a switch to change between 230 V and 115 V. Other models have automatic sensors that switch input voltage automatically, or are able to accept any voltage between those limits. Power supply units used in computers are nearly always switch mode power supplies (SMPS). The SMPS provides regulated direct current power at the several voltages required by the motherboard andaccessories such as disk drives and cooling fans.
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Motherboard
Main article: Motherboard
The motherboard is the main component inside the case. It is a large rectangular board with integrated circuitry that connects the other parts of the computer including the CPU, the RAM, the disk drives (CD, DVD, hard disk, or any others) as well as any peripheralsconnected via the ports or the expansion slots.
Components directly attached to the motherboard include:
* The CPU (Central Processing Unit) performs most of the calculations which enable a computer to function, and is sometimes referred to as the "brain" of the computer. It is usually cooled by a heat sink and fan. Most newer CPUs include an on-die Graphics Processing Unit (GPU).
*The Chipset, which includes the north bridge, mediates communication between the CPU and the other components of the system, including main memory.
* The Random-Access Memory (RAM) stores the code and data that are being actively accessed by the CPU.
* The Read-Only Memory (ROM) stores the BIOS that runs when the computer is powered on or otherwise begins execution, a process knownas Bootstrapping, or "booting" or "booting up". The BIOS (Basic Input Output System) includes boot firmware and power management firmware. Newer motherboards use Unified Extensible Firmware Interface(UEFI) instead of BIOS.
* Buses connect the CPU to various internal components and to expansion cards for graphics and sound.
* Current
* PCI Express: for expansion cards such as graphics, sound,network interfaces, TV tuners, etc.
* PCI: for other expansion cards.
* SATA: for disk drives.
* Obsolete
* AGP: superseded by PCI Express.
* ATA
* VLB: VESA Local Bus, superseded by AGP.
* EISA
* Micro Channel architecture
* ISA: expansion card slot format obsolete in PCs, but still used in industrialcomputers.
* Ports for external peripherals. These ports may be controlled directly by the south bridge I/O controller or provided by expansion cards attached to the motherboard.
* USB
* Memory Card
* FireWire
* eSATA
* SCSI

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Expansion Cards
Main article: Expansion card
The expansion card (also expansion board,adapter card or accessory card) in computing is a printed circuit board that can be inserted into an expansion slot of a computer motherboard or backplane to add functionality to a computer system via the expansion bus.
An example of an expansion card is a sound card that enables the computer to output sound to audio devices, as well as accept input from a microphone. Most modern computers...