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How to Check the Power Supply on the PC?

Running a check on your PC’s power supply is crucial to provide assured system stability and performance you can rely upon. A failed power supply can end up causing numerous issues like component damage or unexpected shutdowns.

If you are checking the power supply on a regular basis, you will be able to locate and then address these concerns even before they start to escalate. So here’s a complete guide on what a PSU is, its functioning, the process of checking the power supply, and much more.

What is a Power Supply Unit & How it Works?

power supply

When we talk of a PC, among many other components that it has, PSU is an important one. PSU means Power Supply Unit. This is basically needed for the conversion of electrical power into regulated power or usable power. Numerous other PC components need this converted power. Also, when it comes to many hardware components, PSU provides them with current, required voltage, power, etc.

These components include a processor, storage devices, motherboards, and more. All in all, in simple terms, PSU, aka Power Supply Unit, helps in converting AC into DC. Here, AC means alternating current, and DC means direct current. DC is something PC components require, and AC comes from the main supply. The conversion is required for these components because they function on low-voltage direct current power. It is usually +3.3V or +5V, or +12V.

Now, how does this whole thing work?

Well, enlisted are steps to understanding how a Power Supply Unit i.e. PSU functions:

How Does a Power Supply Unit (i.e. PSU) Function?

On taking up the alternating current, PSU goes through many steps (listed below) to supply direct current power output as needed.

  1. Step-down: First, a PSU reduces the AC power (which has a high voltage) from your main supply, using a transformer, to a low-voltage level.
  2. Rectification: Now, at this point, the AC power that’s been transformed goes via a rectifier circuit. This one converts this alternating current power into pulsating direct current power.
  3. Filtering: This fluctuating direct current (DC) output coming via this rectifier can’t power the components of a PC, and hence, to avoid these unwanted fluctuations, the use of capacitors is required during the filtering stage. This step ensures the stability of the direct current output.
  4. Regulation: Since many PC components need a stable and accurate voltage level, filtered DC power or direct current power needs to be regulated. This has to be done so it can help with the provision of the required voltage precision. For this purpose, Voltage regulation circuits are used. They tend to first monitor and then make adjustments to the output. It is required so the desired voltage levels can be maintained.
  5. Distribution: After this rectification, filtration, and regulation of the direct current i.e. DC power, it’s now time for the distribution process. The direct current power is now sent to the different connectors and cables. They help supply this power to all the hardware components of your PC.

All in all, what PSU does is that it helps in ensuring your PC is operating smoothly and providing you with reliability. Furthermore, it ensures safety allowance with functions like

  • overcurrent protection
  • short circuit protection
  • overvoltage protection

What are the Different Form Factors of the Power Supply?

Enlisted are 5 different form factors for the power supply:

1. ATX

Preferably used in desktop computers, the ATX form factor for power supply helps power your motherboard and internal components. These could be optical drives, solid-state drives, hard drives, or other peripherals that are attached to the motherboard through many power connectors or SATA.

It further supports graphics cards so the system can work smoothly during heavy tasks like gaming or rendering. It also helps with peripheral connectivity and power distribution one can rely upon.

Size: 150mm x 86mm x 140mm (Approx.)


  • Extensively accessible/easily found
  • Wattage options have a wide range
  • Numerous connectors for wide-ranging hardware
  • Standardized dimensions in terms of case compatibility.
  • Provision of power stability and good efficiency
  • The power-saving functions are supported


  • Larger sizes might not be able to work for compact cases.
  • Case compatibility is needed to ensure a proper fit.
  • Unwanted connectors in terms of a simple build.
  • Cable management is needed for connector quantity.
  • In terms of larger cases, longer cables could be required.
  • It tends to be too large when it comes to compact builds.

2. Flex ATX

Built for compact PCs such as mini-ITX builds, the Flex ATX form factor provides you with space-saving methods. Moreover, it’s well known for fitting into cases with minimal space. You can put these power supplies to use in your entertainment systems, home theater PCs (i.e. HTPCs), low-power setups, and more.

Since they are extremely small, they tend to be portable/mobile. Now, this is why they tend to be ideal as well in terms of portable workstations or LAN parties.

Size: 81.5mm x 40.5mm x 150mm (Approx.)


  • Small size to design/build compact systems
  • Space-saving and hence, best to be used in restricted space cases.
  • Apt for HTPCs along with the media center setups.
  • Contributes to small system portability
  • OEM-friendly when it comes to custom-built systems


  • Lower power output compared to larger ATX supplies.
  • Compatibility is limited when it comes to specific small form factor cases.
  • Less availability in comparison to standard ATX supplies.
  • Connectors are limited in comparison to bigger ATX supplies.
  • Not apt for systems that ask for high-power

3. SFX

These power supplies tend to be utilized in small form factor arrangements. It could be media centers, HTPCs, high-end gaming setups, portable builds, custom projects, etc. They don’t compromise in terms of power and opt for enabling compact builds/designs.

Also, these tend to fit into compact cases smoothly. Further, they help contribute to the system’s portability and provision of enough power to be used for gaming,

Size: 100mm x 63.5mm x 125mm (Approx.)


  • Small size to design/build compact systems
  • Space-saving and hence, apt for limited space cases
  • Shows compatibility with ATX and SFX cases.
  • Apt for small form factor designs and HTPCs
  • Portable
  • Option for improved versions that are highly efficient.


  • Power output is pretty low in comparison to bigger ATX
  • High in price in comparison to basic ATX
  • Limited access in comparison to ATX
  • Limited options in terms of peripheral connectivity or expansion
  • Noise and cooling issues in small designs
  • Difficulties in cable management because of limited space.

4. TRX

The TRX form factor is known to enable the operation and functionality of all TRX devices by the provision of the required electrical power. It further promises a smooth communication ability in different environments on which you can rely.

It comprises functions like solar charging, battery backup, etc. Also, it is compatible with varied power sources, which further ensures that the operations in terms of tactical exercises will remain uninterrupted.

Size: 85mm x 65mm x 175mm (Approx.)


  • Compact build and portable design
  • Apt in terms of field deployments
  • Allows communication you can rely upon
  • Comprises options for battery backup
  • Built for tactical exercises
  • Flexible/Versatile


  • Power capacity is limited
  • Needs to be charged frequently
  • Limited compatibility is seen in terms of power sources
  • High in price/cost in comparison to other standard supplies
  • Restricted compatibility is seen in terms of TRX devices
  • It needs to be managed or monitored carefully

5. BTX

When it comes to the BTX form factor, it is known to provide numerous advantages, like allowing better thermal management and airflow. It further ensures a reduction in the system’s noise and cable clutter.

The layout is known to provide better placement of components. Moreover, it shows support in terms of newer technologies and assured compatibility and signal integrity.

Size: Varies


  • Thermal management is better
  • Improved airflow and noise reduction
  • Better placement of components
  • Enhanced signal integrity
  • Better support in terms of the newest technologies
  • Reduction in cable clutter


  • Limited compatibility/availability
  • Limited options in terms of expansion or upgradeability
  • Incompatible when it comes to legacy hardware or peripherals
  • Manufacturers making/producing a BTX board are limited
  • Costly as the supply is limited
  • It gets difficult to locate compatible cases

What are the Different Types of Power Supplies?

The 3 different types of power supplies involve:

  1. Modular Power Supply
  2. Semi-Modular Power Supply
  3. Non-Modular Power Supply

Let’s discuss each power supply type in detail. Also, there we have provided a differentiation table below for better understanding.

1. Modular Power Supply

This allows the finest cable management because of the detachable cables they come with. This way, users can only connect the needed cables to the components. This further reduces cable clutter, and there is an allowance for customization options.

Now, this allowance provides these users the ability to select and then attach cables. This is done based on what specific requirements they have.

2. Semi-Modular Power Supply

These are basically a blend of cables that are detachable and permanently attached. In this one, when it comes to the main CPU power cables and motherboard, they are fixed.

However, peripheral cables, like SATA or PCIe, are connected/disconnected as required. This way, you get to have the flexibility to manage the cables or run any customizations.

3. Non-Modular Power Supply

In non-modular power supplies, all the cables are attached to the unit on a permanent basis. Hence, all of these cables will have to be managed within the PC case. This also means that you will not be able to remove an unwanted cable.

This condition may end up with a cluttered computer case, or you can say less organized. Moreover, non-modular power supplies tend to be on the affordable side and are put to use when there are budget constraints and cable management isn’t that crucial.

Features Modular Power Supply Semi-Modular Power Supply Non-Modular Power Supply
Cable Management Excellent Good Limited/No
Interchangeable Cables Yes Partially No
Customization Options High Medium Limited
Ease of Installation Easy Easy Easy
Price Expensive Moderate Affordable
Efficiency Varies Varies Varies
Size Larger Moderate Compact
Recommended Use Enthusiast Builds Mid-range Builds Budget Builds

What are the Factors Needed to Consider a Power Supply?

1. Wattage

This basically tells you about the power amount, which it can provide to a system. It has to be enough to manage any power requirements the varied components will have.

You may opt for the consideration of the power requirements of the GPU/CPU, or any different components and then opt for choosing power supplies with wattages, which can give additional capacity in terms of future upgrades.

2. Efficiency

When we consider power supply efficiency, we basically talk of how constructively it converts the alternating current, to direct current to be used for varied system components. Ideally, you should forward to a power supply which comprises high-efficiency ratings like 80 Plus Bronze/Silver/Gold/Platinum/Titanium or so.

When it comes to a high-efficiency power supply, it doesn’t waste a lot of energy in the form of heat. This further results in lesser strain on a cooling system and reduced electricity bills.

3. Form Factor

The form factor basically speaks of its physical shape or size and compatibility in terms of a particular computer case/device. It tells you if the power supplies are getting fit properly or installed in a system or not.

Varied form factors are built to accommodate varied configurations or sizes of different computer cases like Micro-ATX, ATX (Advanced Technology eXtended), Mini-ITX, and so on.

4. Power Delivery Protection

Power delivery protection speaks of various safety features which help in the prevention of any sort of damage to power supplies. It further helps the components related to it.

Furthermore, it involves security against many aspects that could be high or low voltages, overpowering, extreme currents, short circuits, and more. Over and above, these safety features make sure the power supply shuts itself down or gets limited, dodging potential hazards.

5. Rails and Cables

Rails and cables, when we speak of a power supply, are vital components. These help clear the way for the power distribution process to a PC’s varied components.

Rails help supply power at varied voltages to varied components in a PC. Now, what cables do is they help by connecting the power supply to the graphics card, motherboard, storage devices, etc., and it further ensures they can get the required power.

6. Size

Power supplies, when we speak of sizes, have many sizes that involve Micro-ATX, ATX, Mini-ITX, and so on. The highly-common among them is ATX. It is 150mm wide, 140mm deep, and 86mm tall.

There are also small-sized ones to be used for a compact case. Opt for choosing power supplies that complement the case size so it fits perfectly.

How to Check the Power Supply on a PC?

1. Checking the Power Supply on a PC Manually by Opening the PS

To manually check a PC’s power supply, do the following:

  1. First, opt for turning the PC off and then unplugging it.
  2. Opt for opening up the computer case.
  3. Opt for locating the PSU i.e. power supply unit, which is at the back side of the case.
  4. Now, opt for disconnecting the power cables from the various components.
  5. Opt for the removal of fasteners or screws to help protect the PSU.
  6. Look forward to inspecting the PSU for any damages.
  7. You can put to use either a multimeter or a tester (only if available) for the measurement of the voltage output.
  8. Opt to test with the help of a working power supply, which you know, if possible.
  9. Now, opt for reinstalling and securing the PSU.
  10. Shut the case down and then plug in your PC and check whether the power supply is working correctly.

2. Checking the Details of a Power Supply on a PC Through Online Searching

  1. On the PC, and open a web browser.
  2. Using search engines such as Bing, Google, or Yahoo, opt to search your power supply’s brand/model. make sure to add the keyword “specifications” along with the term you will type to search.
  3. Now, opt for pressing the Enter key, or you may just opt for clicking the search button. This will help in initiating the search.
  4. Locate the official pages of a product, manufacturer websites, etc. You may also search for reliable technology review sites.
  5. Opt for clicking on every relevant link to access enough power supply information.
  6. On specifications sheets or product pages, you will notice details like efficiency rating, connectors, wattage, form factor, voltage outputs (rails), and certain other specifications.
  7. Check these details and specifications. This will help in ensuring compatibility with the PC you have.

3. Checking the User Manual

  1. You would have gotten a user manual with your power supply, locate the same or opt for downloading the same using the manufacturer’s website.
  2. Look forward to checking various sections relevant to your power supply.
  3. Check all the installation instructions, specifications, troubleshooting tips, and safety precautions.
  4. Look forward to checking every detail like efficiency rating, connectors, wattage, form factor, voltage outputs (rails), and certain other specifications.
  5. If there is no physical manual accessible to you, you may opt for downloading the same using the manufacturer’s website. You can do so with the help of the name of the product or model number.
  6. Put the table of contents to use, or you may also opt for the search feature to look for relevant sections easily.

Power Supply Checking – FAQs

1. What are the most common PSU problems?

Ans: The PSU problems that are quite common involve the following:
* voltage/current issues at the input and output,
* reversed polarity,
* temperature issues,
* missing external components.

2. How can you tell if your PC power supply is bad?

Ans: The direct answer to this question is that your PC won’t switch on. You may notice everything else on your PC looking damaged. However, if the power supply is working, then the fan might work, and you might also locate power LED lighting up.

3. What causes PSU to fail?

Ans: Environmental causes could be the reason, such as dust/debris/moisture, heat, overloaded power supply, power spikes/surges, and more.

4. What is the first step in troubleshooting a power supply?

Ans: Look forward to checking the power supply’s external connections. See if the power supply cord has been plugged into an outlet that’s functioning or not. Now, opt for the verification of the On/Off switch position.


In the end, PSU is an indispensable component in the PC, which basically helps to transform AC into DC. It comes in varied form factors, which are Flex ATX, TRX, ATX, SFX, BTX, etc. Also, it assures stability in voltage levels. PSUs could be semi-modular, modular, non-modular, or so.

When looking forward to a PSU, consider form factor, wattage, efficiency, cables, protection features, size, and more. To run a check on a PSU, opt for inspecting it. Put a multimeter to use or you may opt for online resources or refer to the manual.

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