How to Troubleshoot a PC With No Boot & No POST

by Norm Dickinson

When a computer completely fails to boot or to provide any sort of power on self-test (POST) beep codes, the cause is either a hardware failure, lack of power or a bad connection. To solve these problems, it helps to start with potential environmental causes first, such as a problem with the AC power being supplied to the computer. From there, a good rule of thumb is to simply start disconnecting items from the computer one at a time until just the CPU, motherboard, RAM and power supply remain connected, and then swapping in known good replacements for them.

Test the AC power to make sure there is power to the outlet. Inspect the back of the power supply to ensure the power cord is fully seated, the power switch is on and the voltage setting is set to the right voltage, which is typically 110 volts.

Inspect the inside of the computer for any signs of burned components, such as capacitors or integrated circuits that are deformed or discolored, and replace the affected expansion card, motherboard, drive or other device if damage is located.

Verify a proper connection for each expansion card, cable, drive and stick of RAM by disconnecting and reconnecting each item without removing it from the system. This can sometimes clean corroded or loose contacts and solve minor problems that prevent the system from booting.

Disconnect the drives and remove all of the expansion cards except for the video card, and try to boot with a bare system composed of only the power supply, motherboard, CPU and cooling fan, RAM, and video. Attempt to start the computer again. If the system boots, reinstall the removed items one at a time until the system again fails to boot, and then replace the component that is causing the failure.

If the bare system fails to boot, swap in known good components for the motherboard, RAM, video card, power supply and CPU until the system boots. Swap components into a working computer one at a time until that system fails to boot in order to locate problem components.


  • check Look for obvious damage or signs of excessive heat. Try the system after each item is swapped out or disconnected to narrow down the cause of the boot failure. Refer to documentation for each device for proper connections, paying close attention to proper orientation and polarity for connectors. Perform a full backup on the working system prior to swapping components into it. Remove the hard drive from the failed computer and connect it to the working computer as a secondary drive to enable access to the files on the drive, and then back it up to an external location prior to attempting to fix the problem preventing the failed computer from booting.


  • close Components inside the computer are sensitive to static shock from electrostatic discharge, and proper care should be taken to always wear an anti-static wrist strap or other preventative device.
  • close CPU pins are easily bent beyond repair and great care should be taken when inserting the CPU into the motherboard CPU socket.

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About the Author

Norm Dickinson began his writing career in 1997 as a content creator for Web pages he designed for clients. His work appears on various websites, focusing on computer technology. Dickinson holds an Associate of Arts in industrial electronics technology and another Associate of Arts in computer science.

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  • photo_camera computer insides image by MLProject from