220-1101 Question 259
Single answerAdvanced Technology Extended (ATX)A technician is replacing a failed motherboard in a desktop PC that uses a standard ATX case and power supply. After installing the new motherboard, the system fans spin but the computer does not complete POST. The technician verifies that the RAM and CPU are seated correctly. Which action should the technician perform NEXT to address the most likely ATX-related issue?
- A
Connect the 4/8-pin CPU power connector from the power supply to the motherboard
- B
Move the front-panel power switch lead to a USB 2.0 header
- C
Replace the 24-pin ATX power connector with a SATA power connector
- D
Disable UEFI in the BIOS to allow the motherboard to receive power
Show answer and explanation
Correct answer: A
Explanation
In ATX systems, motherboard power delivery is split between the main 24-pin ATX connector and an additional 4-pin or 8-pin CPU power connector near the processor socket. A common real-world symptom of a missing CPU power connection is that case fans and indicator LEDs may turn on, but the system will not complete POST. CompTIA A+ expects candidates to recognize standard motherboard and power supply form factors and connectors, including ATX main power and ATX12V/EPS12V CPU power. This aligns with manufacturer installation guidance from motherboard and power supply vendors, which consistently specify that both connectors must be attached for normal operation.
- A. Correct.
Correct. ATX motherboards typically require both the 24-pin main power connector and a separate 4-pin or 8-pin CPU power connector (often labeled ATX12V or EPS12V). If the main connector is attached but the CPU power connector is missing, fans may spin because some power is present, but the system often will not POST. This is a very common issue after motherboard replacement or new system assembly.
- B. Incorrect.
Incorrect. The front-panel power switch connects to the system panel header, not a USB header. Misplacing the power switch lead can prevent the system from powering on at all, but in this scenario the fans already spin, indicating the system is receiving power and the switch is functioning well enough to start the PSU.
- C. Incorrect.
Incorrect. SATA power connectors are designed for storage devices and some accessories, not for motherboard main power delivery. The motherboard requires the proper 24-pin ATX connector and CPU auxiliary power connector. Attempting to substitute SATA power reflects a misunderstanding of ATX power standards.
- D. Incorrect.
Incorrect. BIOS or UEFI settings do not control whether the motherboard receives required physical power connections. If the CPU auxiliary power connector is missing, the board may not initialize regardless of firmware settings. This option confuses firmware configuration with hardware power requirements.