Learn why checking the power supply switch position is the first step when a desktop computer won’t power on, as required for the CompTIA A+ Core 1 220-1101 exam. Understand how the PSU switch affects system startup and basic troubleshooting steps.
Table of Contents
Question
A technician is troubleshooting a desktop computer that won’t power on. The power cable is connected, but pressing the power button does nothing. What should be checked first?
A. Motherboard BIOS settings
B. CPU thermal paste application
C. Power supply switch position
D. Monitor cable connection
E. Hard drive health
Answer
C. Power supply switch position
Explanation
If a PC does not power on at all, checking the power switch on the power supply is a logical first step.
When a desktop computer fails to power on and pressing the power button produces no response, the first thing to check is the position of the power supply unit (PSU) switch. Most desktop PSUs have a physical on/off rocker switch (usually labeled “|” for on and “O” for off) at the back. If this switch is set to the off position, the system will not receive power, regardless of the power cable connection or the state of other components.
Verifying the PSU switch is in the “on” position is a basic but critical troubleshooting step. This check should always precede more complex diagnostics, as it is a common and easily overlooked cause of a completely unresponsive system. Only after confirming the PSU switch is on should you proceed to test the power cable, outlet, or internal hardware components.
CompTIA A+ Core 1 220-1101 certification exam practice question and answer (Q&A) dump with detail explanation and reference available free, helpful to pass the CompTIA A+ Core 1 220-1101 exam and earn CompTIA A+ Core 1 220-1101 certification.