PC won't start ( no power at all)

As grave as this may seem at first blush, a computer that refuses to start isn't usually all that serious. Oftentimes, something outside the computer itself is to blame for a powerless computer.

Power Cord. A loose power cord is usually the problem that prevents your computer from starting. Check each end of the cord to make sure it's firmly in place. Also be sure to check the cables that run to your monitor.

Power supply switch. See if your computer's power supply has an on/off switch that lets you kill power to the PC without removing the cable. This button, located on the back of your computer, can get accidentally bumped.

Surge Protectors, Outlets, and fuses. Make sure the surge protector is firmly plugged into the wall outlet and that the power button on the surge protector is in the on position. If that checks out, see if the devices plugged into other outlets on the power strip are functioning. If not, the surge protector might be to blame. Another likely culprit is a faulty wall outlet. Plug your computer directly into the outlet, sans surge protector. Ensure that the GFCI (ground fault circuit interrupter) hasn't been tripped. If your PC still won't turn on, plug something else, such as a lamp, into the socket to see if it's works. Finally, check your fuse box or circuit breaker to make sure there isn't a blown fuse or tripped circuit. There are also a number of factors inside the computer that could prevent it from starting.

Motherboards And Power Supplies. Most motherboards have a tiny light on them that lights up when the power supply is connected, even if the PC is off. If this LED is lit, your PC is getting power, and your power lies elsewhere. Power supply can sometimes go bad, and if you've followed our troubleshooting steps to this point, you may have a dead PSU (power supply unit). To figure out whether this is the case, use a power supply tester. Follow the manufacturer's instructions to check the well-being of your PSU.

Power Button Cables. If you've recently performed any repairs to your system, it's quite possible that you accidentally pulled the power button cable free from the motherboard. If you spot an unplugged cable, check your motherboard for cables that indicate the prongs that support the power switch. In the event there are no such labels, check your motherboard's users manual.