PC ComponentsPower Supply

What Does a Power Supply Do for a PC?

Pc Power Supply

Are you looking to buy a new computer setup and wondering about the power supply unit functionality? 

Quick Answer

The power supply is an essential part of a computer, as it provides the PC with the electricity that it needs to run and perform the processing functions. The power supply unit or the PSU conducts the alternating current (AC) from the power outlet and converts it into direct current (DC) that your PC needs. 

To help you understand this topic better, we have written a comprehensive guide on what a power supply does for a PC in an easy-to-follow manner. We will also discuss the factors you need to consider before you buy a PSU.

What Does a Power Supply Do for a PC?

The power supply is the most integral part of your computer system and is located at the back, on either left or the right side. As the name suggests, it supplies your computer with the power it needs to perform its function in the form of electric current.

When you connect your computer to any electrical outlet, the PSU starts working by conducting the alternating current or AC and converting it into direct current or DC. 

All of this is done using the switcher technology, as your computer needs a steady and unilateral flow of current to do its job. There are also fans attached to the PSU to help cool it down to avoid any short circuits.o

As you press the power button on your PC, it sends a signal of 5 volts to the PSU to indicate it to turn on. The cables connected to the PSU then start converting and sending the signals to the various parts of your computer, including the hard drives, motherboard, and case electronics. 

From there on, the motherboard is responsible for evenly distributing the signals to other computer parts.

The power of a PSU is expressed in watts (W) and usually ranges from 300W to 1000W. This is why you must choose a PSU depending on your computer’s power needs.

How To Choose the Power Supply Unit for Your Computer

Now that you know what the power supply does for your computer, it is crucial to determine how to choose one and what factors to consider.

Factor #1: Wattage

The most important thing to look out for when getting a PSU is to decide how much wattage you require. If you have a more complex PC setup with cooling systems, dual GPUs, and a high-end motherboard, you will need a PSU with higher wattage to keep your system running smoothly. 

On the other hand, if you have a simpler system, you don’t need to spend a lot of money buying a higher-power PSU. 

Sometimes, you may need clarification about how much power your computer might need. In that case, you can use any online wattage calculator and add the relevant details to get your system’s recommended power supply wattage.

Factor #2: Protection

As the PSU is connected to the most important parts of your computer, sometimes power fluctuations in the unit can lead to irreversible damage to your system. This is why you must consider PSU protection. 

Many PSUs come with built-in protection that detects and shuts itself down in case of power fluctuations, called “Over Voltage Protection”. 

You can also go the extra mile and get a surge protector to give the power supply unit a higher level of protection against short circuits in case of an increase in power.

Factor #3: Efficiency

Regarding PSU efficiency, there is a rating system that is determined by how a PSU performs on a 115-volt system. The most common rating for a PSU is “80 PLUS”, which further increases to “80 PLUS Bronze”, “80 PLUS Silver”, “80 PLUS Gold”, “80 PLUS Platinum”, and so on.

The higher your PSU rating is, the less power it consumes while giving the best output. 


In this guide, we have discussed what a power supply does for your computer. We have also discussed the factors you need to consider when buying a PSU for your computer. 

Hopefully, your query has been resolved, and you have a better understanding of the power supply unit and can decide which one to choose for your PC.

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