The Power Supply converts the alternating current (from the wall) to the lower voltage DC power that can be used for the computer components.
more info: https://www.computerhope.com/jargon/p/power-supply.htm
RAM [Random Access Memory] Holds small bits of info which are lost when the computer is turned off. Each row of this memory can be plugged into the motherboard
video: https://www.youtube.com/watch?v=wfJ7G6MBYkE (2:46)
CPU [Central Processing Unit] This is about 2” square and has pins all the way around. It may already be attached to the motherboard. The brains of the computer.
Video: https://www.youtube.com/watch?v=NT5WkJw35NQ (4:26)
Motherboards are Large and have slots for other boards and devices to be plugged into it. Also known as the main board or logic board, it is a printed circuit board with chips & connectors. The motherboard usually has spots for the CPU, memory, hard drives, and video cards to connect. It also has controllers for the peripherals such as the monitors, keyboard and CD/DVD drives
more info: https://computer.howstuffworks.com/computer-hardware-pictures.htm
video: https://www.youtube.com/watch?v=b2pd3Y6aBag (6:27)
Nearly all computers have heat sinks, which help keep the CPU cool and prevent it from overheating. ... This combination is creatively called a "heat sink and fan," or HSF. The fan moves cool air across the heat sink, pushing hot air away from the computer.