CompTIA A+ Core 1 (220-1201)HardwareMedium
A technician is troubleshooting a desktop computer that powers on but displays no video output. The power LED on the monitor is amber/orange, indicating no signal. The system does not emit any beep codes. Which of the following is the MOST likely cause?
- ACorrupt operating system
- BDisconnected video cable
- CFaulty RAM module
- DFailed power supply unit
Show answer & explanationAnswer & explanation
Correct answer: B. Disconnected video cable
If the computer powers on, the monitor LED is amber (no signal), and there are no beep codes, it suggests the system is passing POST but not sending a video signal to the monitor. A disconnected or improperly seated video cable is a very common and easily overlooked cause of this specific symptom.
Why the other options are wrong
- A. A corrupt operating system would prevent the OS from loading, but the system would still typically display the BIOS/UEFI POST screen or a boot error message.
- C. A faulty RAM module would typically cause beep codes and sometimes prevent the system from powering on or passing POST.
- D. A failed power supply unit would likely prevent the computer from powering on at all, or cause intermittent power issues, not just a lack of video signal while the system appears to be running.
No Video Troubleshooting
A systematic approach to diagnosing why a computer powers on but displays no image on the screen.
- Check physical connections first (cables, power).
- Listen for beep codes to identify hardware failures.
- Test with known-good components (monitor, cable, GPU).
Memory trick: See No Screen? Start Simple Solutions.