The case and power supply unit

The case and power supply unit

                                          Casing

The outer look of CPU box is casing where all physical parts are attached. It is home of system board.

Types of casing: AT and ATX casing

                      ⦁Desktop casing

                      ⦁Tower casing

                            Selecting the case unit is mostly a matter of deciding for a style. Both types of case vary by size and profile. Whereas the desktop case sits on the desktop, the tower case is designed to stand upright and can be much larger. Before choosing the case we should think about our location requirements for computer. If we need to update computer at a later stage, may be adding more hard drives or other devices, then we might consider a tower with more room for add-ons.

Power supply; SMPS (switch mode power supply)

The power from the main line is 220v AC with a lot of interference. So it cannot be directly fed to the computer. For this purpose SMPS is used between the computer and the main line to convert 220v AC to a well regulated 12V DC, 5V DC, 3.3V DC with polarity of positive or negative. Here, in SMPS transformer is a device which makes voltage up or down, in this case 220V is converted into 12V, rectifier is a circuit which converts AC into DC and the process is called rectification.

Usually, the electronic components and circuits in the system board use the 5V power and the motors in the diskdrives use 12V power. Standard power supplies normally rate between for 200W to 300W, which is enough for any normal computer. But if you intend to build a machine with multiple hard drives and lot of other internal/external devices, try to get a 300W supply. Better too much than too little.

Another important factor is the cooling fan, which normally comes with the power supply. Always make sure that you get a working cooling fan with the power supply as excessive heat can cause permanent failure of the components. This is another good reason for buying a large case; a bigger case means less heat. If you decide for a second fan, make sure it supports the airflow with in the case and blows in the same direction as the power supply fan.

A power supply has three types of connectors used to power the various devices with in the computer. These are:

⦁ berg connector (Floppy drive power connector) 

⦁ molex connector (HDD, Optical Disk)

⦁ system connector

⦁ 2*2 extra power supply

The back of power supply contains three things. They are:

⦁ The computer power connector

⦁ The monitor’s power connector

⦁ The exhaust fan port

         UPS (Uninterruptible Power Supply)

UPS is a device that stores the electricity and supply to the computer automatically incase of electricity failure. It is used for computer to prevent the loss of data and damage of computer parts caused due to electricity failure. Each and every components of computer can sustain a fixed current capacity so; fluctuation of voltage may damage these components. That’s why we have to use UPS, Volt Guard, Stabilizer, etc. to maintain the voltage fluctuation.