Troubleshooting a Computer That Powers On Briefly and Then Turns Off: A Guide for DIY PC Builders
Building a custom PC can be an exciting experience, but it can also come with its share of troubleshooting challenges. One common issue faced by enthusiasts is when the system powers on briefly—showing fans spinning—and then shuts down immediately, with no display output. This article explores potential causes and solutions, based on a real-world scenario from a recent user case.
Scenario Overview
A user recently upgraded their system with a new Power Supply Unit (PSU) and a new graphics card (AMD RX 570). After installation, the system exhibited a brief power-up phase where fans spun, but then immediately turned off, and no display signal was produced. Additional observations included:
- The PSU was tested successfully with a PSU tester.
- Both the PSU and GPU fans stop spinning after about a second.
- No power is delivered to connected USB devices.
- The user suspects a possible voltage or amperage mismatch on the motherboard’s power rails.
Potential Causes and Troubleshooting Steps
- Insufficient Power or Incorrect Power Delivery
Power supply specifications are critical for system stability. The user notes their new PSU (Seasonic Focus GX-750W) provides approximately 20A at 100W on the 3.3V and 5V rails, whereas the motherboard potentially expects around 30A and 150-225W combined on these rails.
Action Steps:
- Verify the wattage and current ratings of the PSU on the +3.3V and +5V rails via the datasheet or PSU manufacturer specifications.
- Ensure the PSU is rated to supply sufficient current on these rails to support your motherboard and peripherals.
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Consider testing with a different PSU that matches or exceeds the motherboard’s expected power requirements.
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Compatibility and Power Supply Testing
Although a PSU tester was used, these devices primarily confirm basic functionality but might not detect all issues. Using a multimeter for detailed voltage measurements can offer a more accurate assessment.
Action Steps:
- Use a multimeter to check the voltages on the motherboard power connectors during system startup.
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Confirm that the 3.3V and 5V rails are within acceptable ranges (generally ±5%).
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Motherboard and Hardware Compatibility
Incompatibility or damage could cause the system to shut down immediately after power-up.
Action Steps:
- Reset CMOS/BIOS settings to default.
- Remove non
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