A technician is servicing a desktop workstation that is in a completely unpowered state. Pressing the chassis power button produces no fan movement, LED indicators, or diagnostic beeps. The technician tests the power supply unit (PSU) using a standalone PSU tester, which confirms that all output voltage rails (+12V, +5V, +3.3V) are within proper operating specifications. Which of the following diagnostic steps should the technician perform next to isolate the cause of the failure?
- Momentarily bridge the front-panel power switch header pins on the motherboard using a jumper or small conductive tool.Cevap
- BReplace the installed memory modules with high-density SO-DIMM modules.
- CPerform a complete motherboard BIOS/UEFI firmware reflash via a USB drive.
- DImmediately replace the existing power supply with a higher-wattage model to increase voltage output.
Cevap
Momentarily bridge the front-panel power switch header pins on the motherboard using a jumper or small conductive tool.
The correct action is to test the chassis power button switch by shorting the front-panel power pins on the motherboard. Since the PSU passed testing on all voltage rails, the motherboard is receiving standby power but may not be receiving the momentary ground signal from the case power button required to initiate full system power-on.
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Power switch bypassing and power state isolation diagnostics