Power Supply Unit or PSU is a hardware that is responsible for converting the consumer supply current to consistent electronic circuit current of computer. If must have noticed a usual Car or Motorbike repairing shop – some of them have a box like unit with various output terminals, they test the bulbs and other electrical and electronic components by attaching with it. Practically this common unit of a garage serves the same purpose – both converts our consumer supply AC 230 Volt current to various DC output. As quite obviously, using such a unit is not possible for a computer, it is made sophisticated for specific usage for a computer. This is the basic of Power Supply Unit (PSU) of Computer. But, actually Power Supply Unit is not so simple electrical part.
Voltage factor of Power Supply Unit
A typical desktop computer needs a supply of 300 to 500 watts. Power requirement of a PC depends on the system and principal use. The task of computer power supply is production of small voltages, the working voltages in a computer is usually -12V,-5V, +12 V, +5 V and +3.3 V. Processors, RAM and chipsets work internally with lower voltage which the motherboard regulates. The cost of a typical Power Supply Unit depends on the quality, brand, the output power range and highest possible pay load that the Power Supply Unit can handle.
Functions of a Power Supply Unit
Switching Power Supply is used for Power Supply Unit to bring down the voltage. It is not a transformer as using a transformer will increase a Power Supply Unit’s weight and moreover, it is not so sophisticated. The example of the car garage unit we said at the beginning, quite obviously uses a transformer as for a bulb, .05 volt variation will not matter, but for a Computer will matter.
Moreover, in U.S. standard, usually 120 Volt consumer supply is used, but in all European Countries and India, its 240 Volt, 50 Hz supply, as the Power Supply Unit manufacturers needs an uniform manufacturing, you will notice a slider switch button in most Power Supply Unit.
Form factor and Power Supply Unit
In Wikipedia, you will get all the huge technical details of form factors of a Power Supply Unit, they have
copied written it from various manufacturing sources. Honestly, so much head spinning technical things of a Power Supply Unit is useless to know for a common user. Simply know that the low voltage (-5V) is usually used for expansion cards and higher for units with mechanical parts – like the hard disk. Form Factor determines which kind of Power Supply Unit is to be used. These form factors are – AT, ATX, LPX, BTX, DTX. These form factors of a motherboard is a set, where the individual components, such as CPU and slots are arranged on the motherboard.