Check your power supply wattage on Windows without opening the case

The fastest way to find your power supply's rated wattage is through Windows itself. Open the Settings app, go to System, then About. Scroll down to find Device specifications — the "System type" line tells you whether you're running 32-bit or 64-bit Windows, but that's not what you need. Instead, open Command Prompt (search for "cmd" in the Windows search bar), right-click it, and select Run as administrator.

Type this command exactly: wmic logicaldisk get name and press Enter. This won't show power supply info — instead, use this command: Get-WmiObject -Class Win32_SystemEnclosure in PowerShell (search for "PowerShell" and run as administrator). The output will show your chassis information, but the most direct method is to look at your system's BIOS. Restart your PC, press Delete, F2, or F12 during startup (the key varies by motherboard), and look for a section labeled Power, System Information, or Hardware Monitor. Your power supply wattage is often listed there.

If those routes don't work, the easiest method is to check your PC's original documentation or receipt. If you built the PC yourself, your power supply box or manual will have the wattage printed on the label. For laptops, the wattage is printed on the power adapter itself.

Key Takeaways

  • Your power supply's wattage is printed on the unit itself if you can see it, or listed in your PC's BIOS under System Information or Hardware Monitor.
  • Windows does not display power supply wattage in Settings or Device Manager, so checking the BIOS or physical label is the most direct route.
  • A power supply that is five to seven years old may be nearing the end of its lifespan even if it still powers your PC.
  • Unusual shutdowns, random restarts, or burning smells are signs your power supply is failing and should be replaced soon.
  • You can estimate whether your power supply has enough capacity by adding up the wattage of your CPU, GPU, and storage, then choosing a unit rated 20 to 30 percent higher.

Open the case and read the label directly

The most reliable way to check your power supply is to look at it. Power supplies have a large label on the side or back that lists the rated wattage, voltage, and amperage. If your PC is a desktop, shut it down completely, unplug it from the wall, wait 30 seconds, then open the side panel. The power supply is usually a metal box in the bottom corner or back of the case.

The label will show a line that reads something like "Total Power: 650W" or "Max Output: 750W." Write down this number — it's what you need to know. If the label is faded or missing, the model number is printed nearby. You can search that model number online to find the specifications. For laptops, you cannot open the power supply, so check the power adapter brick instead — the wattage is printed on a label on the back or bottom.

Check the age of your power supply

Power supplies degrade over time, and a unit that is five to seven years old may be nearing the end of its useful life even if it still works. To find the manufacture date, look at the label on the power supply itself. Some manufacturers print the date in a format like "2019-03" (year and month). Others use a code — check the manufacturer's website to decode it.

If you cannot find a date on the unit, check your PC's purchase receipt or warranty documentation. If you built the PC yourself, look at your invoice from the retailer or your email receipt. Knowing the age helps you decide whether to replace the unit before it fails. A power supply that is eight years or older should be considered for replacement, especially if it powers a high-end GPU or CPU.

Look for signs of power supply failure

A failing power supply often shows warning signs before it stops working completely. The most common sign is random shutdowns or restarts that happen without warning, especially when you're running demanding programs like games or video editing software. Your PC may also restart when you first turn it on, or it may shut down after a few minutes of use.

Other warning signs include a burning smell coming from the case, visible damage to the power supply casing, or a fan inside the power supply that no longer spins. If you hear a loud buzzing or humming noise from the case that wasn't there before, the power supply may be failing. Do not ignore these signs — a failing power supply can damage other components in your PC, so replacement should be a priority.

Calculate whether your power supply has enough capacity

Your power supply needs to be rated higher than the total power draw of your components. To estimate this, find the wattage of your CPU and GPU. For CPUs, search your processor model (like "Intel Core i7-13700K") and look for the TDP (Thermal Design Power) number — this is roughly how much power it uses. For GPUs, search your graphics card model and find the same TDP number.

Add these two numbers together, then add 100 watts for your motherboard, storage drives, and fans. For example, if your CPU is 125W and your GPU is 320W, your total is 445W. A good rule is to choose a power supply rated 20 to 30 percent higher than this total, so in this case a 550W or 650W unit would be appropriate. This headroom keeps the power supply from running at maximum capacity all the time, which extends its lifespan.

Use third-party software to monitor power draw

If you want to see how much power your PC is actually using right now, several free programs can show you this information. HWiNFO is a popular choice — read it from hwinfo.com, install it, and run it. The program displays real-time power consumption for your CPU and GPU, though it may not show the total system power draw.

Another option is to use your GPU manufacturer's software. NVIDIA users can read NVIDIA Control Panel, and AMD users can read AMD Radeon Software. Both show GPU power consumption in real time. These tools help you understand whether your current power supply is working hard or has headroom, but they do not replace a physical inspection of the unit itself.

Frequently Asked Questions

Can I run my PC with a power supply that is lower wattage than recommended?

No. A power supply that is too weak will cause random shutdowns, especially when you run demanding programs. The PC will shut down to protect itself when power demand exceeds what the supply can deliver. This can also damage the power supply or other components over time.

How do I know if my power supply is 80 Plus certified?

Look at the label on the power supply. If it is 80 Plus certified, the label will say "80 Plus" followed by a tier like Bronze, Gold, or Platinum. This means the power supply converts at least 80 percent of wall power into usable power, wasting less energy as heat. Certification does not affect whether the unit works with your PC, but it does mean lower electricity bills.

What should I do if my power supply is making noise?

A small amount of fan noise is normal, especially under load. If the noise is new, loud, or sounds like buzzing or grinding, the power supply may be failing. Shut down your PC, unplug it, and consider replacing the power supply soon. Do not wait for it to fail completely, as this can damage other parts of your computer.

Is it safe to replace my power supply myself?

Yes, if you follow basic precautions. Shut down your PC completely, unplug it from the wall, and wait 30 seconds before opening the case. Unplug all cables from the old power supply, unscrew it, and remove it. Install the new one in reverse order. If you are uncomfortable doing this, a computer repair shop can do it for you.

Why does Windows not show my power supply wattage?

Windows does not have direct access to power supply information because the power supply is a separate hardware component that does not report to the operating system. The BIOS can sometimes show this information because it runs before Windows loads, but even then it depends on your motherboard's design.