The Reason for a Motherboard Not Lighting Up When the PSU is Switched On: BIOS or PSU Failure?
When your motherboard fails to light up upon switching on the power supply unit (PSU), it can be a concerning issue. Speculating why a motherboard might not light up is crucial, as it could indicate either a bios update requirement for new CPU support or a PSU failure. This article aims to provide clarity and actionable information to help you diagnose both scenarios.
Understanding the PSU Fan Behavior
A broken power supply unit (PSU) that fails to shut down or start would typically not spin its fans. However, the absence of fan spin, in itself, does not always indicate a PSU problem. A more reliable sign is that a well-paying PSU will not start its fans as long as the temperature remains within normal limits.
It's important to distinguish between a PSU issue and the behavior of a motherboard. While a PSU not spinning its fans might suggest a problem with the PSU, it may also indicate other factors, such as advanced cooling mechanisms in premium PSUs. In some cases, complete lack of fan spin might be normal, provided the PSU is under no thermal stress.
Measuring PSU Voltage with a Multimeter
In order to determine if the PSU is functioning correctly, one effective method is to measure the voltage output using a multimeter. For instance, with a standard Molex connector, you can check the 5V and 12V outputs by connecting the red/black probes (multimeter's positive/negative) to the yellow/black wires (the power connector for a CD or older IDE disk).
This checking process is crucial as simply turning on the PSU switch isn't enough to ensure power is being emitted. The PSU requires a special signal to initiate power-up. This signal is typically activated by the power button on the computer case, although it can also be influenced by BIOS settings regarding the power state after a power loss.
BIOS and Power State Settings
The BIOS (Basic Input/Output System) plays a significant role in managing the power state of a motherboard. One such setting is related to how the system returns to a previous power state following a power outage.
In some cases, the inability of a motherboard to light up might be due to a BIOS configuration. For example, if your system is set to return to a previous power state after a blackout, it might momentarily halt the power-up process, leading to the perception that the system is not lighting up. To resolve this, it's advisable to check the BIOS settings and make any necessary adjustments.
Furthermore, BIOS updates can be crucial for supporting new CPUs. If you've recently upgraded your CPU, updating your motherboard's BIOS may be necessary. Manufacturer documentation often provides guidance on necessary updates and the steps to perform them.
Conclusion
Determining the reason for a motherboard not lighting up when the PSU is switched on requires a systematic approach. It could be due to a BIOS setting or a PSU failure. By understanding the behavior of the PSU fans, measuring the PSU voltage output, and checking the BIOS settings, you can narrow down the cause and take appropriate action.
Keywords: motherboard, power supply unit (PSU), BIOS