A school computer lab has 20 identical computers. Recently, several systems started showing some issue: the computer powers on (fans spin and lights turn on), but nothing appears on the monitor and no startup sound is heard. The monitors and cables have been tested and are working fine. A technician swaps the operating system drive from a working computer into one of the faulty systems, but the problem still persists .

Which of the following is the most likely cause of the issue? 

Why C is the most likely cause: The symptoms described—fans spinning and lights turning on, but no display output (Black Screen) and no startup sound (POST chime)—indicate that the computer is failing to complete its POST (Power-On Self-Test). Because this failure occurs at a hardware level before the computer even attempts to read the storage drive, swapping the operating system drive had no effect. The issue is likely a failure in a core component such as the RAM, Motherboard, CPU, or Power Supply Unit (PSU).

Why the other options are incorrect:

A is incorrect: If the operating system were corrupted, you would typically still see the motherboard splash screen (BIOS/UEFI logo) or receive an error message (like "No bootable device found") before the screen goes blank. Furthermore, swapping in a known working OS drive would have fixed the issue if it were just a software corruption problem.

B & D are incorrect: Graphics drivers and monitor resolution settings are managed entirely by the operating system. Since the failure happens immediately upon powering on—before the operating system even begins to load—drivers and OS display configurations cannot be the cause.