Computer power supply is the electric source of all components of a computer. Though it is one of the neglected one compare to the other parts, power supply is a must for a system. Often this part of a computer gets failure and most of the time it is not serviceable.
It will be easier and cheaper to replace than try to service it.
You should give due attention like you do for other components when you choose or replace the power supply unit.
The function of power unit is to convert the electrical power (AC) comes from wall socket to a suitable type and voltage (DC) so that each component of a computer works properly.
Luck of proper supply of power will damage a computer system. The power supply receives 120 or 230V and converts into 3.3V, 5.5V and 12V. Why different converted power? That is because all components of a computer system don’t need the same power.
For example, motherboard and cards use 3.3V. The most power demand parts such as Fan and drives need 12V to operate.
Usually, power units comes with a case, however, it is a requirement to know the factors behind this unit before picking a new one. Power supplies available on the market have different size and shape that will fit into a particular type of computer case. This is called Form factor, layout and dimensions of a unit.
When you are going to replace a malfunction power unit, you should choose the exact form factor that will go with the existing case of your computer.
There are different power supply form factors, but ATX and LPX are the popular types found in most systems.