How to Check for Disconnected Computer Power Cable Connections

If your computer doesn't turn on, check all the cabling, from the PC's power cable to the wall

By
Tim Fisher
Photo of Tim Fisher, Lifewire GM and Writer
Tim Fisher
Senior Vice President & Group General Manager, Tech & Sustainability
  • Emporia State University

Tim Fisher has more than 30 years' of professional technology experience. He's been writing about tech for more than two decades and serves as the SVP and General Manager of Lifewire.

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Updated on April 20, 2023

What to Know

  • Make sure power cable fits firmly in the three-pronged power-supply port on the rear of the computer case.
  • Verify other end of power cable is securely plugged in to wall outlet, surge protector, power strip, or battery backup.
  • If applicable, verify that surge protector, power strip, or battery backup is securely plugged into the wall outlet.

This article explains how to check a typical desktop computer for loose or improperly connected power cables. This could be the culprit if your computer doesn't turn on or if it shuts off abruptly.

01
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Check the Power Cable Behind the Computer Case

Picture of a computer power cable connection

Power cables often wiggle loose from PC cases over time, or sometimes after being moved around. Checking every point where electricity is delivered to the computer system is usually a first step when a computer isn't receiving power.

The first place to start is with the power cable that connects at the rear of the computer case. It should fit firmly in the three-pronged port on the power supply.

If, when pressing firmly into the power supply, the PSU itself falls inward into the case, then it's not properly secured to the case. This might happen if you were recently working in your computer but forgot to secure those screws. You'll have to open the computer case to fix this, just make sure the power cable is unplugged.

02
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Verify PC Power Cable Is Securely Plugged In

Picture of power cables plugged in to a power strip

Follow the power cable from the back of the computer case to the wall outlet, surge protector, or power strip that it is (or should be) plugged in to. If your PC is attached to a battery backup unit, follow the cable there.

Make sure the cable is securely plugged in.

03
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Verify Power Strip or Surge Protector Is Securely Plugged in a Wall Outlet

Picture of a power cable plugged in to a wall outlet

If the power cable from the PC case was plugged into the wall outlet in the last step, your verification is already complete.

If your power cable is plugged into a surge protector or a power strip, ensure that it's securely plugged into the wall outlet. The same is true for battery backup: make sure the backup unit is firmly plugged in to its power source (likely the wall).

If everything is plugged in to the computer, check for disconnected monitor power cable connections. Your computer might turn on fine, but it could appear to be off if the monitor is blank.

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