The power supply unit (PSU) is vital for all desktop PCs. This component handles the conversion of power from alternate current (AC) to direct current (DC). Your PC parts can't work with AC and require a stable, reliable DC supply that a power supply provides. Everything connects to the power supply, albeit some parts indirectly through the motherboard. Should your PSU encounter issues, buy a PSU from an unreputable brand, or overload it with more powerful parts, you risk causing irreparable damage. Thankfully, power supplies are designed so they shouldn't go out with a bang. Here are some signs the PSU could be on its way out.

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The inability to turn on the system is one way to be sure something is wrong with the PC. There's a good chance the PSU is at fault for a PC not turning on, especially if it was previously working and nothing has been changed. A motherboard, CPU, or GPU issue will still see the system turn on but fail to pass the power-on self-test (POST). If no visible LEDs are present on your motherboard or GPU, we're likely looking at a failed power supply. One thing to try is to remove the front I/O panel connectors to your motherboard and use a flat-head screwdriver to short the two power-switch pins. This will rule out a problem with the physical power button.