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 come back with positive results. What hardware part would you check next?
1 PSU
2 PS/2
3 NIC
4 EXT-USB HDD
5 SSD
The correct answer and explanation is :
Correct Answer: 1. PSU (Power Supply Unit)
Explanation:
When a desktop PC doesn’t consistently power on or randomly shuts down, yet the hard drive (HDD) and RAM have tested positive (i.e., no faults found), the next most likely culprit is the Power Supply Unit (PSU).
The PSU is responsible for converting electrical power from the wall outlet into usable power for all internal PC components. If the PSU is malfunctioning or degraded — which often happens in older PCs — it can cause intermittent power loss, random shutdowns, and failure to boot up. This is especially common in aging systems where capacitors inside the PSU may have worn out, leading to unstable voltage or current delivery.
Why not the other options?
- PS/2 (keyboard/mouse port): Faulty PS/2 ports may cause input issues but do not lead to random shutdowns or failure to power on the entire system.
- NIC (Network Interface Card): A defective NIC may cause network connectivity problems, but it does not impact the system’s ability to remain powered on or boot properly.
- EXT-USB HDD (External USB Hard Drive): External drives are peripheral devices and are not critical to the PC’s power operation. While they may draw power from USB ports, they won’t cause random shutdowns unless a severe short circuit occurs — which is rare and easily testable.
- SSD (Solid State Drive): A faulty SSD may cause boot errors or OS crashes, but it typically does not cause the computer to power off or prevent it from turning on altogether.
Conclusion:
Given the symptoms — intermittent startup and unexpected shutdowns — the Power Supply Unit (PSU) is the most likely hardware component at fault. Testing or replacing the PSU is the recommended next step in diagnosis.