Troubleshooting no-video PCs: Identify the least likely root cause A desktop PC powers on but shows no video on the display. Among common culprits, which is the least likely to cause a no-video symptom during POST or boot?

Introduction / Context:
When a PC shows no video, a technician prioritizes failures that occur before or during the Power-On Self-Test (POST). Understanding which subsystems are involved before the disk is accessed helps triage quickly.

Given Data / Assumptions:

• System powers up but display remains blank or out of sync.
• We are considering causes from power, CPU, memory, and video to storage.
• POST typically initializes CPU, chipset, memory, and video before touching the OS drive.

Concept / Approach:

No-video conditions are most often due to issues on the path to generating a video signal: seating of the GPU, RAM errors preventing POST beeps, motherboard/CPU faults, or inadequate power. Storage devices are initialized later; a failed hard drive usually shows video with an error like “No boot device.”

Step-by-Step Solution:

Verification / Alternative check:

Bench tests with a known-good bootable USB often still produce video and BIOS screens even when the HDD is missing or failed, confirming that storage is not a prerequisite for video.

Why Other Options Are Wrong:

• Loose video card: common cause of black screen.
• Defective RAM (bank zero): prevents POST, leading to no video and beep codes.
• Defective CPU: system cannot execute POST; results in no-video.
• Low AC outlet power: can cause unstable PSU output and no initialization.

Common Pitfalls:

Spending time swapping HDDs early. Always verify POST, beeps, and display output before storage troubleshooting.

Final Answer:

Crashed hard drive