A technician is replacing a failed motherboard in a enterprise desktop system with a Micro-ATX form factor board. The new system board features an 8-pin EPS12V power socket, four DDR4 memory slots, two PCIe x16 expansion slots, and two M.2 slots. During assembly, the system fails to power on and perform POST when the power button is pressed, despite the standby LED on the motherboard being lit. The technician verifies that the main 24-pin ATX power cable is securely connected. Which of the following is the most likely cause of this issue?
- The dedicated 8-pin EPS12V CPU power cable was not connected to the motherboard.Cevap
- BThe PCIe auxiliary 6+2 pin cable was plugged into the 8-pin motherboard CPU power socket.
- CThe RAM modules were installed in single-channel configuration instead of dual-channel slots.
- DAn M.2 drive using the SATA protocol was installed into an M.2 slot keyed exclusively for NVMe PCIe drives.
Cevap
The dedicated 8-pin EPS12V CPU power cable was not connected to the motherboard.
Modern motherboards require both the 24-pin ATX main power connector and an auxiliary 4-pin or 8-pin EPS12V connector. The 24-pin ATX connector provides standby power (+5VSB) and basic logic power, which illuminates onboard LEDs. However, the dedicated 8-pin EPS12V cable supplies the high amperage +12V power needed by the processor. Omitting the EPS12V connection prevents the CPU from powering on and halts the system power cycle.
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Motherboard Auxiliary CPU Power Connectors (EPS12V vs 24-pin ATX)