Power Supply Unit (PSU)

What is Power Supply Unit (PSU)?

A Power Supply Unit (PSU) is a hardware component that provides electrical power to a computer or other electronic device. It converts AC power from the wall outlet into DC power that is suitable for the computer’s components to use.

PSUs come in different wattage ratings and connector types to match the requirements of different computer systems.

Understanding Power Supply Unit (PSU) in a Computer

What is a PSU in a Computer

The computer consists of a lot of hardware. And the Power Supply Unit or the PSU is also a part of the computer.

It is also hardware. By the name, one can understand the power supply unit of the PSU supplies power to the other parts of the computer.

It helps to convert the power which is given from the outlet into a power supply which is then used by the other parts of the computer.

The PSU is usually located at the top back of the computer. But these days the power supply is placed at the bottom of the computer case right at the back.

The outlet which is in the wall is plugged in and it is then converted from Alternating Current to Direct Current. Which is a continuous flow of power.

Knowing the difference between the Alternating Current and the Direct Current is essential. It is an amazing work of Technology.

Which is always sidelined by the other famous components like the CPU, the motherboard, and the others.

If there is no power supply then the computer will not be able to start.

The PSU comes in many sizes, especially which can fit in most of the cases for computers.

The width and height may be the same but the length and how long it is depends on manufacturers.

Some popular power supply unit manufacturers are CORSAIR, Ultra, and even CoolMax. These come with the computer when purchased or even while customizing.

Many users are unable to see what the computer supply usually consists of because it is mostly placed at the back and in a case. It consists of a fan that transfers the air out of the computer case.

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It contains three prolonged ports (male). Which is connected to the power source.

One of them consists of two switches, a power switch or even a power supply voltage switch.

There are colorful wires into which they are connected to the different parts.

Then it supplies power. For instance, there are wires which are connected to the fans, motherboard, GPU, and many more.

One most important component of the PSU is the fan and if it does not work then it causes a lot of problems.

A power supply unit usually cannot be repaired.

Many users avoid opening the power supply unit. The rating of the power supply unit of the PSU is in terms of wattage.

The more powerful the computer the more Wattage the PSU provides to the other parts of the computer.

Both the personal computers consist of the same components of the PSU. But there is the outer appearance that differs.

In the desktop computer, the PSU comes in a metal box for proper protection and it becomes very heavy.

But in laptop computers, it comes in a thin plastic box they cannot be internally attached.

So they are externally plugged in to make the laptop run.

Also, the power supply units are named depending on how much power it can give.

The power supply unit comes with the label which informs the users about PSU’s information.

Like how much power one voltage line can give. Many electronic markets sell PSU and they have various prices for all kinds of PSU.

The user should choose the PSU according to the budget and how much power it can deliver.

It also depends on the demand of the Power the Other components of the computers want.

Types of Computer Power Supply

Choosing the right power supply is important. Because if there is no power supply the computer will not work at all.

The traditional power supply or the AT power supply is also known as the Advanced Technology power supply.

It is the predecessor of the ATX power supply. It is the first power supply used for computers.

Then the need for computers was raised. The AT power supply provided a wattage of 250.

Which was less than the others. Therefore, the need for Advanced Technology power supply had dropped drastically.

ATX or the Advanced Technology Extended. These are an advanced type of power supply for computers. ATX also has a motherboard designed.

Therefore, to match the ATX motherboard one needs to purchase an ATX power supply.

It was developed in the year 1995 by the famous manufacturer Intel. It outperformed the traditional power supply.

The ATX power supply provided plus 3.3 voltage extra voltage rail. It even provides a “soft off” feature.

The power supply is turned off by the software. And it is allowed by the ATX power supply.

Lastly, the ATX power supply comes with a 20 pin connector which is single. And which is the main power connector.

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The ATX power supply rating is below 70% and its efficiency is quite low.

The ATX12V has become very popular these days. It has outperformed the ATX power supply.

The ATX12V has many variants or versions. Those versions are different from one another.

The ATX12V is an advanced power supply. And it is a bit better product than the ATX form factor.

Adding a few better specifications like the extra 4oin  connectors.

It also comes with a 12V connector. The 12V connector helps deliver power to the professor exclusively.

The newest version is the ATX12V version 2.4 which is used by many computers.

They consist of 24 pin connectors that come in the same size as the ATX power supply.

One can use any ATX power supply motherboard with an ATX12V power supply.

But the ATX motherboard allows 20 pin connectors. There has to be a lot of space where the 24 pin connector can be used as a better alternative.

The remaining four pins are not used.

And space is an important factor here. But the ATX power supply cannot be connected to an ATX12V motherboard because of the number of pins.

12V is quite efficient and its efficiency is above 80% rate which is better than the traditional power supply AT and ATX.

The other power supply includes below:

Computer Power Supply Voltages

**PSU or the power supplies are used to convert the Alternating Current or AC coming from the output to Direct Current or DC which is lower. Voltages vary and it sounds very simple to understand.

The supply comes in voltages like 3.3 volts, 5 volts, and 12 volts.

These voltages do not necessarily have to be exact. But it can only vary till a certain point be it below or above.

But if it goes extreme then it may cause problems. The voltage is a product of Watts. The Power supply usually used these days are as follows:-

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Power Supply Functions

Questions & Answer:

Where is the PSU located in a computer?

Previously the PSU was located at the top, back of the computer. But, now it is located at the bottom of the computer case, at the back.

How long does a PSU last?

It depends on how well it is handled. Usually, the PSU lasts 5-7 years. And if handled very well then it can last more. Brand and quality also depend.

What causes PSU to fail?

If the fan stops working and also due to overheating. Also, if the PSU is badly handled then it will lead to failure. Here also it depends on the quality and how well it works.


This hardware does not stop being manufactured because of the importance it holds in the world of computers.

No power supply, no functioning of the computer.

Being so important. One should take proper care of the computer. And also not to fiddle with the power supply unit.

It is very difficult to repair and is very dangerous to fiddle with.