PC won’t spin up an IDE/ATA hard drive at power-on: What is the most likely cause when the hard disk does not spin?

Introduction / Context:
When a desktop IDE/ATA hard drive fails to spin at power-on, the fault is usually in the power path rather than the data path. Recognizing the most probable failure saves time during triage and reduces the risk of data loss.

Given Data / Assumptions:

• Symptom: the drive does not spin (no vibration, no whine).
• Standard 4-pin peripheral power (Molex) connector is used.
• No prior indication of firmware or logical errors.

Concept / Approach:
Spinning the platters requires 12 V and 5 V from the PSU via the Molex connector. A loose or oxidized Molex connection is common and immediately prevents motor startup. By contrast, a bad data cable or wrong jumper affects detection and transfer but does not stop the motor from spinning. Viruses and system-board configuration do not physically inhibit the spindle motor at power-on.

Step-by-Step Solution:

Verification / Alternative check:
Measuring voltage on the Molex (yellow ~12 V, red ~5 V, black grounds) confirms power presence. Observing in another system further isolates the fault to drive or PSU.

Why Other Options Are Wrong:
Bad data cable: the drive typically still spins. Incorrect jumper: affects master/slave detection, not motor power. Virus: cannot prevent motor spin at POST. 'tfad system board': not a meaningful diagnosis and unlikely compared to a simple loose power connector.

Common Pitfalls:
Forgetting that SATA/IDE drives can feel very quiet; always touch the drive frame to confirm vibration. Avoid hot-plugging Molex on non-hot-swap systems.

Final Answer:
loose Molex connector