Computer Power Supply Troubleshooting
Computer Power Supply Troubleshooting
Warning! You must unplug your ATX power supply from the wall before working inside the case.
Troubleshooting PC failures starts with the power supply. In fact, it's easier to diagnose failures where the computer won't turn on at all as opposed to more intermittent issues. The flowchart below is one of 17 hardware diagnostic flowcharts included in my book, "Computer Repair with Diagnostic Flowcharts - Revised Edition." The expanded text is modified for this web published version, and the diamond symbols are linked to the text.
ATX PC Power Supply Diagnostic Flowchart
The first step in the troubleshooting process is simply determining if the power supply is coming on. You can usually hear those mechanical components in PC systems that make rotational noise when they are powered up. This usually includes the hard drive as it starts up the electric motor to keep the discs spinning, and some fan noise is pretty much a constant with modern computers. Your PC should also give a single beep if it passes its internal start-up diagnostic, and there are always status LED's to tell you the system is on, though some home PC builders don't bother connecting them. If your hearing isn't good, you can check to see if the power supply fan is creating a breeze. Monitors are powered independently, so unless you're looking at a notebook PC, a live screen doesn't indicate a working power supply.
Return to Diagnostic Chart
If power isn't coming on, take the time to double check that the cord is plugged into a live socket and firmly seated in the back of the power supply. It's not necessary to own a DVM (Digital Volt Meter) to check your power outlet. Unplug the power supply cord from the outlet and plug a working lamp into the very same socket to test it. Don't assume that all the sockets in a power strip are working just because the power strip status light is lit. I'm always coming across power strips with one or more bad outlets. The
Warning! You must unplug your ATX power supply from the wall before working inside the case.
Troubleshooting PC failures starts with the power supply. In fact, it's easier to diagnose failures where the computer won't turn on at all as opposed to more intermittent issues. The flowchart below is one of 17 hardware diagnostic flowcharts included in my book, "Computer Repair with Diagnostic Flowcharts - Revised Edition." The expanded text is modified for this web published version, and the diamond symbols are linked to the text.
ATX PC Power Supply Diagnostic Flowchart
The first step in the troubleshooting process is simply determining if the power supply is coming on. You can usually hear those mechanical components in PC systems that make rotational noise when they are powered up. This usually includes the hard drive as it starts up the electric motor to keep the discs spinning, and some fan noise is pretty much a constant with modern computers. Your PC should also give a single beep if it passes its internal start-up diagnostic, and there are always status LED's to tell you the system is on, though some home PC builders don't bother connecting them. If your hearing isn't good, you can check to see if the power supply fan is creating a breeze. Monitors are powered independently, so unless you're looking at a notebook PC, a live screen doesn't indicate a working power supply.
Return to Diagnostic Chart
If power isn't coming on, take the time to double check that the cord is plugged into a live socket and firmly seated in the back of the power supply. It's not necessary to own a DVM (Digital Volt Meter) to check your power outlet. Unplug the power supply cord from the outlet and plug a working lamp into the very same socket to test it. Don't assume that all the sockets in a power strip are working just because the power strip status light is lit. I'm always coming across power strips with one or more bad outlets. The