Power supply

The power supply is used to supply power to the motherboard and disk drives. The power supply varies depending on the power of the computer, although the standard volts that it provides are 3.3, 5 and 12 volts. The 3.3 volts, along with the 5 volts are used for digital circuts while the 12 volt is used to power the fan and drive motors  It converts the home AC (Alternating Current) current into DC( Direct Current) current which is what the computer requires. When the computer is in standby, it runs 5 volts so that when the power button is pressed, it then tells the power supply to start up

The power supply connects to the motherboard and disk drives via a number of wires called a ribbon. This ribbon uses a 20-pin and 4-pin connector. The 4-pin connector connects to the hard drive and disk drives while the 20 pin connector connects to the motherboard, while also enabling the link so that the motherboard can identify the primary and slave hard drives.

There are a variety of reasons as to why you would want to replace the hard drive, such as if you have a powerful graphics card, or have a powerful computer