A lot of power supplies have an external switch on the back of the unit. Before moving on, check to see if it hasn’t been switched off by accident or by another person. [2] X Research source
It’s usually a good idea to also check inside your build — with the computer disconnected from the wall socket — to ensure that there are no loose or malfunctioning cables on the inside as well. This process will depend on your specific computer, so follow the manufacturer’s instructions to reach the inside of your PC. [3] X Research source
It’s possible that HDD issues are not related to a faulty power supply. If you recently moved or hit your PC, check to see if you didn’t jostle anything on the inside that may be giving you errors.
The simplest rule of thumb is that the new unit should be exactly the same width as the old one. It’s fine if the new unit is a bit longer, as long as it will still fit into your case. Do not hesitate to ask the salesperson or technician for help in identifying the correct unit to purchase.
If your system doesn’t start up correctly here, your failing power supply could have taken out the motherboard.
