Random access memory is a type of data storage used in computers. It takes the form of integrated circuits that allow the stored data to be accessed in any order — that is, at random and without the physical movement of the storage medium or a physical reading head
It's connect to main board
Modem
A modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information
Video card
A video card is an item of personal computer hardware whose function is to generate and output images to a display.
It's connect to AGP slot
Sound card
A sound card is a computer expansion card that can input and output sound under control of computer programs
It's connect to PCI slot
Hard disk drive
A hard disk drive (HDD), commonly referred to as a hard drive or hard disk, is a non-volatile storage device which stores digitally encoded data on rapidly rotating platters with magnetic surfaces. Strictly speaking, "drive" refers to a device distinct from its medium, such as a tape drive and its tape, or a floppy disk drive and its floppy disk.
It's connect to main board
Main board
Main board is the center of the equipment in computer connected.All of the equipment in the computer must connect to main board.
It’s connecting to case, and every equipment in computer.