A customer complains that his old tower PC doesn't always turn on and randomly shuts off for hours. The HDD and RAM memory tests both come back with positive results. What hardware part would you check next?

To address the issue of a tower PC that doesn't always turn on and randomly shuts off, despite positive HDD and RAM tests, follow these steps:

Step 1: Define the Problem

The key issue is the PC's inconsistent power behavior, which includes not turning on and shutting off randomly.

Step 2: Break Down the Problem

1. Power Supply Unit (PSU): Check if the PSU is delivering consistent power.
2. Motherboard: Inspect for any visible damage or faulty connections.
3. Cooling System: Ensure that the cooling system is functioning properly to prevent overheating.
4. Cables and Connections: Verify that all cables and connections are secure and undamaged.

Step 3: Apply Relevant Concepts

• PSU Testing: Use a multimeter or PSU tester to check the output voltages.
• Motherboard Inspection: Look for blown capacitors or burnt areas.
• Cooling System Check: Confirm that fans are spinning and thermal paste is applied correctly.
• Cable Inspection: Ensure all power and data cables are properly connected.

Step 4: Analysis, Verify and Summarize

• PSU: If the PSU fails the test, it is likely the cause of the problem.
• Motherboard: Any visible damage could indicate a need for replacement.
• Cooling System: Overheating can cause shutdowns; ensure proper cooling.
• Cables: Loose or damaged cables can interrupt power supply.

Final Answer

The next hardware part to check is the Power Supply Unit (PSU), as it is a common cause of power-related issues in PCs.