220-1101 Question 302
Single answer3.6 Given a scenario, install the appropriate power supply.A technician is replacing the failed power supply in a small form factor workstation used for CAD work. The original PSU label shows 300W, an 80 PLUS Bronze rating, a 24-pin motherboard connector, a 4-pin CPU power connector, and one SATA power lead. The replacement PSU physically fits the case and has the same 24-pin and SATA connectors, but it only includes an 8-pin PCIe connector and no 4-pin CPU power connector. What should the technician do NEXT to complete the repair correctly?
- A
Install the replacement PSU because the 24-pin motherboard connector is the main requirement and the system should boot without the CPU power connector
- B
Use a Molex-to-CPU adapter so the replacement PSU can power the processor without checking the motherboard documentation
- C
Obtain a PSU that includes the required CPU power connector and matches the system's form factor and power requirements
- D
Install the replacement PSU and connect the 8-pin PCIe cable to the 4-pin CPU power header because the connectors provide similar voltage
Show answer and explanation
Correct answer: C
Explanation
When installing a replacement power supply, the technician must verify more than just wattage and whether the unit physically fits. A proper PSU replacement must match the case form factor, provide sufficient wattage for installed components, and include the correct native connectors for the motherboard, CPU, storage devices, and any add-in cards. In this case, the critical issue is the missing CPU power connector. A standard 24-pin ATX connector powers the motherboard generally, but the CPU usually also requires a dedicated 4-pin or 8-pin power connection. Best practice is to confirm connector requirements in the motherboard or system documentation and use a PSU designed for that system's needs rather than substituting unrelated cables. This aligns with common manufacturer guidance from motherboard and PSU vendors, which warns against mixing connector types such as PCIe and CPU power leads and emphasizes matching PSU connectors to the board's specifications.
- A. Incorrect.
Incorrect. The 24-pin ATX motherboard connector is necessary, but it is not sufficient by itself. Most motherboards also require a dedicated CPU power connector, commonly 4-pin ATX12V or 8-pin EPS12V, to power the processor voltage regulation circuitry. Without the proper CPU power connection, the system will typically fail to POST or power on correctly.
- B. Incorrect.
Incorrect. While adapters exist, using a Molex-to-CPU adapter as a first choice is not best practice for a workstation repair. It can introduce compatibility and power-delivery concerns, especially if the PSU was not designed with the required CPU power lead. The technician should first verify proper native connectors and supported power output rather than relying on an improvised solution.
- C. Correct.
Correct. The technician should select a PSU that matches the physical form factor, wattage needs, and required power connectors, including the motherboard's CPU power connector. In this scenario, the replacement unit is missing a required connector, so it is not the appropriate PSU for the system even if it fits physically and has the 24-pin main power connector.
- D. Incorrect.
Incorrect. PCIe power connectors are intended for graphics cards, not motherboard CPU power headers. Even if some connectors may appear similar in shape or pin count in other scenarios, PCIe and CPU power cables are not interchangeable and are keyed differently on compliant hardware. Forcing or misusing them can damage the motherboard or PSU.