220-1101 Hardware and Network Troubleshooting Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  Power button on the front panel

  Why this is correct

  The power button is a momentary-contact switch that momentarily shorts the 'Power On' pins on the motherboard front-panel header, signaling the PSU to start. Since the power supply works when its 'PS_ON' pin is jumpered to ground, the fault lies upstream in the signal path — and the most common failure point there is the switch itself. A worn, oxidized, or internally broken switch can fail to close the circuit, so pressing it yields no response even though standby power (e.g., the board's standby LED) remains active.

• ✗

  Front panel header cable

  Why it's wrong here

  The front panel header cable is only a pair of passive wires connecting the power button to the motherboard's power button header. While a loose, disconnected, or broken cable would also prevent the power-on signal, it is a less common failure than the switch itself because the cable is not subjected to repetitive mechanical stress. This can be verified by momentarily shorting the two power header pins with a screwdriver: if the system powers on, the motherboard is fine and the fault is either the switch or the cable — but the cable is simply copper wire, so the switch's internal contact is statistically more likely to fail.

• ✗

  Motherboard

  Why it's wrong here

  A faulty motherboard could fail to latch the power-on signal even when the button and cable are intact, but this is a less likely root cause because the standby LED is lit, indicating the board's power management circuitry is receiving 5V standby power and is operational. Additionally, if the power pins are shorted manually and the system still does not start, only then does the motherboard become a primary suspect. In typical bench troubleshooting, the immediate and most cost-effective test is to replace or bypass the power button before condemning the motherboard, as switch failure is far more common than a defective ATX power-on circuit.

• ✗

  CPU

  Why it's wrong here

  A defective CPU almost never prevents the system from powering on; it causes a no-POST failure where fans spin, lights turn on, and the PSU is running, but the system produces no video or beep codes. The power-on sequence begins with the motherboard's power-on circuit and the PSU, and the CPU is only initialized after the main power rails are stable. Since this system does not react to the power button at all, the fault resides in the power-on signaling path — not in the CPU, which becomes relevant only after power is already delivered.

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