How to Check Power Supply Wattage

When you’re using your computer, whether it’s for gaming, working, or casual browsing, the power supply is what keeps everything running smoothly. It’s crucial to know the wattage of your power supply to ensure it’s providing enough power for your computer’s components, especially if you’re planning to upgrade or troubleshoot issues. Not sure where to start? Don’t worry! We’re going to cover various methods to find out the wattage of your power supply unit (PSU).

how to check power supply wattage

Check the Power Supply Label

Each power supply has a label with its specifications, including the wattage. To find this, you’ll need to open up your computer case.

Detailed Steps:

  1. Shut down your computer and unplug all cables.
  2. Open the computer case by removing the side panel. This might involve unscrewing screws or releasing a latch, depending on your case.
  3. Locate the power supply unit, which is typically at the top or bottom rear of the case.
  4. Look for a label on the PSU with a bunch of specifications. The wattage should be listed there, often in a large font or bolded.
  5. Write down the wattage number for future reference.


Checking the label directly on the PSU is an accurate way to determine its wattage. The main benefit is that you get the information straight from the source. However, this method does involve opening up your computer, which might be daunting for some users.

Use a Power Meter

An external power meter device can gauge your system’s power usage, which can help indicate the PSU’s wattage.

Detailed Steps:

  1. Purchase an external power meter meant for computing devices.
  2. Plug in your computer’s power cable into the power meter.
  3. Plug the power meter into the wall outlet.
  4. Turn on your computer and let it run at its typical load.
  5. Read the display, which shows how much power your computer draws from the PSU.


Using a power meter can give you an idea of your system’s power usage, which should be less than the PSU’s total wattage. It’s a less technical method, but it won’t give you the exact wattage capability of your PSU, just the power being used.

Manufacturer’s Website

Often the manufacturer’s website has detailed specs for your PSU, including wattage.

Detailed Steps:

  1. Identify the make and model of your PSU from the label inside your computer.
  2. Go to the manufacturer’s website and enter the model in their search bar.
  3. Find the product page, which should have a detailed specification sheet or a downloadable manual.
  4. Look for the wattage information in the specs or manual.


Searching the manufacturer’s website is a convenient way to find out the PSU wattage without physically accessing the PSU. However, it requires knowing the model number which might not be readily available if you can’t find it on the PSU itself.

Original Purchase Documents

Original receipts or purchase documents often have the PSU model and wattage listed.

Detailed Steps:

  1. Locate the original purchase receipts or invoices for either your computer or the PSU if bought separately.
  2. Look through the documents for the PSU specifications.
  3. Note the model and the wattage that will typically be listed.


Reviewing purchase documents is easy and doesn’t involve handling computer hardware. However, the downside is that it requires having kept the original purchase information, which might not always be the case.

Retailer’s Website

If you bought the PSU from a specific retailer, they might have your purchase history on their website.

Detailed Steps:

  1. Visit the retailer’s website where you purchased the PSU.
  2. Log into your account if necessary.
  3. Access your purchase history.
  4. Find the purchase listing for your PSU and view the details for the wattage information.


Online retailer records can be a handy reference, assuming the purchase was made online and the account and history are still accessible. In some cases, the specific details might not be detailed enough to provide the wattage.

Ask the Manufacturer

Many PSU manufacturers provide customer service that can help identify your PSU wattage.

Detailed Steps:

  1. Locate the contact information for the PSU manufacturer.
  2. Prepare the model of your PSU or any identifiable information.
  3. Reach out to the manufacturer through their customer service portal.
  4. Ask for the wattage information of your PSU model.


Customer service can be incredibly helpful, offering accurate information directly from the source. The potential downside is that this can be time-consuming and requires you to wait for a response.

Check Your Computer’s Documentation

Your computer, especially if it’s pre-built, may have come with documentation listing the PSU wattage.

Detailed Steps:

  1. Find the user manual or any official documentation that came with your computer.
  2. Look through the sections about hardware specifications.
  3. Search for details regarding the power supply for wattage information.


Manufacturer documentation is reliable and easy to access if you have kept it. However, many users lose this documentation over time or it might not include the specific details needed.

Use a PSU Calculator

Online PSU calculators can help estimate the wattage your computer should have based on its components.

Detailed Steps:

  1. Go to an online PSU calculator like the one from be quiet! or Cooler Master.
  2. Input your computer’s specifications, including CPU, GPU, RAM, and others.
  3. Submit the details to get an estimated power supply wattage requirement.


While PSU calculators can give you an estimated idea of what wattage your setup requires, it doesn’t tell you the actual wattage of your PSU. It’s a good starting point if you’re considering an upgrade.

Inspect PSU Connectors

Some PSU connectors can indicate a higher-wattage power supply, especially if you have a modular PSU.

Detailed Steps:

  1. Open your computer case.
  2. Inspect the PSU connectors. More connectors, especially higher powered ones like 8-pin CPU or GPU connectors, typically mean a higher wattage PSU.
  3. Check the cable labels, sometimes they indicate the wattage they’re designed for.


While not a definitive method, inspecting the connectors can give you a rough idea, especially if you’re experienced with computer hardware. It can be misleading, though, as it’s not a precise indication of wattage.

BIOS or UEFI Interface

The interface that manages your computer’s hardware settings might provide information about the power supply.

Detailed Steps:

  1. Restart your computer and enter the BIOS or UEFI settings, usually by pressing a key like Delete, F2, or Esc during the startup.
  2. Navigate through the menus looking for power settings or hardware monitors.
  3. Check to see if the PSU wattage is listed—though this is uncommon.


The benefit of this method is that it’s non-invasive, but the downside is that it’s unlikely many BIOS or UEFI interfaces will display the PSU wattage.

In conclusion, knowing your computer’s PSU wattage is vital for ensuring your system runs smoothly and for planning any upgrades. While there are multiple ways to check this, some may require a bit of detective work or getting your hands dirty inside your computer’s case. Whether you use direct methods like inspecting the PSU label or indirect methods such as online calculators and customer support, ensure that your system’s power needs are adequately met.


Q: Why is it important to know my power supply wattage?
A: Knowing your power supply wattage helps ensure your PSU can handle the power requirements of your system, particularly important if you’re upgrading or adding new components.

Q: Is there any way to check my power supply wattage without opening my computer?
A: Yes, you can check through purchase documents, retailer’s websites, manufacturer’s customer service, or use an online PSU calculator to estimate the requirement based on system components.

Q: Can the BIOS/UEFI tell me my PSU’s wattage?
A: Generally, no. Most BIOS or UEFI interfaces do not provide information on PSU wattage, though they may offer other system power information.

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