Why won’t your computer start?

Your desktop computer is not starting when you turn on the power. The system lights up, but the computer never displays anything on the screen. You’ve checked the voltage coming out of the wall outlet with a multimeter, and it appears to be normal. You also checked the power connector on the motherboard, and found that the 12 volt pin is only showing 6 volts. What is the most likely cause of this issue?

A) The power supply is faulty

B) The motherboard is faulty

C) The computer devices that use 12 volt power are faulty

D) The wall outlet voltage is mismatched to the power supply

E) Did I forget to pay the power bill?

The answer: A) The power supply is faulty

The power supply takes the AC power from the wall outlet and outputs many different DC voltages. These different voltage rails are used by the motherboard for different tasks. For example, many of the powerful computer processors use 12 volt power, and other components might use 3.3 volts.

Want to know more? Watch “Troubleshooting Power Supplies.”

Troubleshooting power supplies requires some specialized tools and some common troubleshooting techniques. In this video, you’ll learn about circuit testers, the value of a good multimeter, and how to use these tools to troubleshoot power outlets and power supplies.