II. Power supply

A case control, and (usually) a cooling fan, and supplies power to run the rest of the computer, the most common types of power supplies are AT and BabyAT (old) but the standard for PCs actually are ATX and Micro ATX.

III. Storage controllers

Controllers for hard disk, CD-ROM and other drives like internal Zip and Jaz conventionally for a PC are IDE/ATA; the controllers sit directly on the motherboard (on-board) or on expansion cards, such as a Disk array controller. IDE is usually integrated, unlike SCSI Small Computer System Interface which can be found in some servers. The floppy drive interface is a legacy MFM interface which is now slowly disappearing. All these interfaces are gradually being phased out to be replaced by SATA and SAS.

IV. Video display controller

Produces the output for the visual display unit. This will either be built into the motherboard or attached in its own separate slot (PCI, PCI-E, PCI-E 2.0, or AGP), in the form of a Graphics Card.

V. Removable media devices

VI. Internal storage

Hardware that keeps data inside the computer for later use and remains persistent even when the computer has no power.

VII. Sound card

Enables the computer to output sound to audio devices, as well as accept input from a microphone. Most modern computers have sound cards built-in to the motherboard, though it is common for a user to install a separate sound card as an upgrade.

VIII. Networking

Connects the computer to the Internet and/or other computers.

IX. Other peripherals

In addition, hardware devices can include external components of a computer system. The following are either standard or very common.

1. Input

1.1 Text input devices

1.2 Pointing devices

1.3 Gaming devices

1.4 Image, Video input devices

1.5 Audio input devices

2. Output

2.1 Image, Video output devices