Is your PC acting weird—random restarts, crashes, or not turning on at all? Before you start replacing expensive parts, the issue could be something simple: your power supply unit (PSU). In this easy-to-follow guide, you’ll learn how to check the power supply on a PC — using both software and hardware tools — so you can find out if your PSU is healthy or needs to be replaced.
Let’s break everything down step by step.
Why It’s Important to Know How to Check Power Supply on PC
Think of the power supply like the heart of your computer. It sends electricity to every part of your system.
Checking your power supply can help you:
- Fix random restarts or crashes
- Prevent damage to your other computer parts
- Make your PC last longer
- Plan for upgrades the right way
Whether something’s wrong with your computer or you just want to make sure everything’s working great, it’s a good idea to check the PSU.
Understanding the Basics: What Is a PSU?
A PSU (Power Supply Unit) changes the electricity from your wall outlet (AC power) into the kind your computer parts need (DC power). It powers your:
- CPU (brain of your PC)
- GPU (graphics card)
- Motherboard
- Drives (SSD, HDD), and more
PSUs come in different power levels, usually shown in watts (like 500W, 650W, etc.), and they also have efficiency ratings like 80 Plus Bronze, Gold, or Platinum.
A bad PSU can cause shutdowns, make your computer freeze, or even damage other parts.
Software Methods: How to Check Power Supply on PC Without Opening It
Want to see how your power supply is doing without opening your PC? You can use software tools that check the voltage coming from your PSU.
These voltage readings help you know if your PSU is delivering power correctly.
⚠️ Note: Software checks can help, but they’re not 100% perfect. Think of them as a starting point.
1. Use a Hardware Monitor Program
Try downloading free tools like:
- HWMonitor
- Open Hardware Monitor
- HWiNFO64
- AIDA64 (trial version available)
These programs show information like:
- +12V
- +5V
- +3.3V
Here’s what the correct voltage ranges should be:
- +12V: Between 11.4V and 12.6V
- +5V: Between 4.75V and 5.25V
- +3.3V: Between 3.14V and 3.47V
If any voltage is way off, your PSU might be failing.
🔎 Tip: Run a game or a stress test to see how the voltages behave under pressure.
2. Use BIOS or UEFI Settings
You can also check power info directly in your BIOS or UEFI:
Here’s how:
- Restart your PC.
- As it starts, press a key like Delete, F2, or F10 (watch for the message on the screen).
- In BIOS, look for “Hardware Monitor” or “System Health.”
- Find voltage levels (VCORE, +12V, +5V, +3.3V).
You can compare them to the normal ranges above.
⚠️ Note: BIOS readings show voltage when the computer is sitting idle. To see how your PSU works under load, you still need software tools or hardware testing.
Hardware Methods: How to Find Power Supply on PC and Test It Manually
If your PC isn’t turning on or you want a more accurate test, it’s time to physically check your PSU.
These methods are more direct and can give you a clear answer.
1. How to Find the Power Supply in Your PC
To locate your power supply:
- Look at the back of your PC.
- The PSU is usually where the power cord connects.
- It’s a box with a fan and may be on the top or bottom of your case.
Look for a label with details like:
- Wattage (like 600W)
- Brand and model
- Efficiency rating (80 Plus, etc.)
This info is helpful if you’re thinking about upgrading.
2. Do the Paperclip Test (Jumpstart Method)
If your PC won’t turn on, this basic test checks if the PSU works at all.
⚠️ Important: Be careful with this method. Do not touch any metal parts while the PSU is plugged in.
How to do it:
- Unplug your PC from the wall.
- Disconnect the big 24-pin cable from your motherboard.
- Bend a paperclip into a “U” shape.
- Insert one end into the green wire (pin 16), and the other into any black wire (ground).
- Plug in the power cord and turn the PSU on.
✅ If the PSU fan spins, it works at a basic level.
❌ If nothing happens, the PSU could be dead (or fanless — check your model).
Note: This doesn’t test voltages — it only tells you if the PSU turns on.
3. Use a PSU Tester
A PSU tester is a small device you plug into your power supply to get voltage readings.
Why it’s great:
- Safer than the paperclip test
- Simple to use
- Shows correct voltages on a screen
Steps:
- Unplug your PC and open the case.
- Connect the PSU’s cables (like the 24-pin and CPU 8-pin) to the tester.
- Plug in your PSU and turn it on.
- Read the results—make sure all voltages are in the normal range.
PSU testers cost around $15 to $30 online, and they’re super handy.
4. Use a Multimeter (Advanced Method)
A multimeter can show accurate voltage readings, but it’s best for more advanced users.
With a digital multimeter, you’ll:
- Set it to measure DC voltage.
- Turn on your PC or PSU.
- Place the black (ground) probe into a black wire.
- Place the red probe into:
- Yellow wire for +12V
- Red wire for +5V
- Orange wire for +3.3V
Compare the results to the standard safe ranges.
⚠️ Only do this if you’re comfortable with electronics and safety procedures.
Signs Your Power Supply Might Be Failing
Watch for these warning signs:
🚫 PC won’t power on
⚡ Random restarts or shutdowns
🔥 Burning smell or strange noises
🌀 PSU fan not spinning or too loud
🖥️ Blue screen of death (BSOD)
🧨 Visible damage like melted wires or bulging parts
If you notice any of these, test your PSU or consider replacing it.
How Often Should You Check or Replace a PSU?
Most PSUs last 5–7 years or more—if they’re good quality and used properly. But heat, dust, and power spikes can wear them out faster.
Best tips:
- Check your PSU every 6–12 months, especially if you notice problems
- Test it after adding heavy parts like a new graphics card
- Replace it if it’s over 5 years old and giving issues
Final Thoughts: Keep Your PC Powered Up and Running Smoothly
We’ve covered a lot, so here’s a quick recap!
✅ Software checks (like HWMonitor or BIOS) can show real-time voltage levels
✅ Hardware tests (like the paperclip, PSU tester, or multimeter) are more accurate
⚠️ Watch for signs of PSU failure like restarts, shutdowns, or a dead PC
🛠️ Test regularly and replace a PSU if it’s old or showing problems
Your computer’s power supply is one of the most important parts. It keeps everything running—and protects your valuable parts.
So whether you’re fixing problems or just doing a check-up, now you know how to check power supply on PC the right way.
👉 Ready to start? Download HWMonitor or grab your PSU tester and see how things look!
Was this guide helpful? Share it with friends who build PCs or leave a comment with your own tips!
💡 Thanks for reading — stay safe, stay powered, and happy computing!