5.5 - Troubleshooting RAID, RAM and system faults
CompTIA A+ Core 1 objective 5.5 covers RAID, RAM and general system faults. When a RAID 5 array reports one failed disk but still works, the correct action is to replace the failed drive so the array can rebuild - the parity keeps data available meanwhile. If only half the installed RAM shows in the OS after adding memory, check module seating and compatibility and remember 32-bit or BIOS limits can cap addressable memory. A loud grinding or rattling noise that changes with load points to the fans or a spinning hard drive. And when you need recorded hardware, driver or system events, the Event Viewer logs are where to look. Expect scenario questions that describe an array, memory or noise symptom and ask for the correct diagnostic step.
RAID 5, one disk failed, still runs = replace the drive so it rebuilds. Only half the RAM shows = seating/compatibility + 32-bit/BIOS limits. Grinding noise with load = fans or spinning HDD. Recorded errors = Event Viewer.
Practice questions
1. A RAID 5 array reports one failed disk but still works. What is the correct action?
- Ignore it since the data is safe
- Replace the failed drive so it can rebuild (correct answer)
- Delete and recreate the whole array
- Convert the array to RAID 0
RAID 5 tolerates one failed disk but is now degraded — replace it promptly; a second failure means data loss.
2. After adding RAM, only half the installed capacity shows in the OS. What should you check?
- A generic Windows graphics card driver
- Module seating, compatibility, and 32-bit/BIOS limits (correct answer)
- The monitor's connected video display cable
- The office document network printer
Missing RAM can be a mis-seated/incompatible module, a 32-bit OS (~4 GB cap), or a BIOS setting — reseat and verify compatibility.
3. A PC makes a loud grinding/rattling noise that changes with load. Which parts should you inspect FIRST?
- The RAM modules and the CPU
- The fans and any spinning hard drive (correct answer)
- The external monitor and the keyboard
- The wired network interface card
Mechanical noise usually comes from fans (bearings/obstruction) or a failing spinning HDD — inspect/replace as needed.
4. Where should a technician look for recorded hardware/driver errors and system events on Windows?
- The Notepad editor
- The Event Viewer logs (correct answer)
- The Calculator app
- The Paint app
Event Viewer records system, application and security logs — invaluable for diagnosing crashes, services and driver errors.
5. A phone produces no sound from its speaker even at full volume, but Bluetooth audio works. Likely cause?
- The phone battery is completely dead
- Faulty speaker or wrong audio routing (correct answer)
- The SIM card has been removed
- Internal storage is almost full
If Bluetooth audio works but the speaker doesn't, suspect a failed/obstructed speaker or audio stuck routing to another device.
6. A PC intermittently loses a USB device that works fine on another machine. What is a good check?
- Reinstall the operating system
- Try another port or a powered USB hub (correct answer)
- Replace the device's own cable
- Turn off the Windows firewall
Intermittent USB drops can be power management suspending the port, marginal power, or driver issues — disable USB selective suspend, update drivers.