If your PC won’t turn on, but the motherboard light is on, the most probable cause can be a faulty power button on the casing. Or perhaps, the wiring has gone bad that connects the button to the motherboard’s power switch headers. In that case, you can still jump-start the PC.
However, if the alternate starting methods fail, you might be dealing with faulty hardware parts. However, you can look for POST codes or swap the parts with spare ones for further confirmation.
Why Won’t My PC Turn On but Has Power?
If your PC has power, probably indicated by the lit-up lights on hardware parts, try built-in tests like POST and beep codes. To clarify, POST codes are 2-digit visual signs that manufacturers use to interpret error messages. Some units even display the code, which you can match with the user manual to start diagnosis.
Likewise, beep codes are the auditory resemblance of POST codes. But here, we use the frequency of the beeps instead of actual digits as the diagnostic method. For example, the absence of a graphics card may result in three consecutive beeps.
PC Won’t Turn On But Motherboard Light Is On – How to Troubleshoot
If your PC won’t turn on, but the motherboard light is on, it is either the power button on your PC case or its internal wiring causing the trouble. Well, it’s not like there cannot be other issues since hardware failures also trigger motherboard LEDs. But the chances are pretty low, given hardware errors usually trigger warning systems.
What Does It Mean When the Motherboard Light Is On
When the motherboard light is on, it indicates that the motherboard is getting power from the PSU. However, most motherboards will come with more than one LED with different colors that lit up in certain conditions, often internal errors.
For example, a red LED generally points out faulty internal components or incorrect plugging issues. To say the least, it indicates problems with hardware components like the RAM, CPU, and GPU. Besides, a dead CMOS (complementary metal-oxide-semiconductor) battery or some boot errors can turn the light on too.
Motherboard Lights on but No Power
You can start the troubleshooting phase by checking whether or not there’s a built-in power button on your motherboard. Upon finding it, use it to turn on your PC as you would do with the actual power button. And once it boots up successfully, you can be sure that the issue is with your PC case.
Don’t freak out if you cannot find it, as many motherboard units skip it. No matter what, you can still turn your system on following the steps below.
1. Locate the Power Switch Headers
Look up close, and you should find two power switch headers with labels such as PWR_SW or anything similar. There will be ‘+’ and ‘–’ markings as well. Yet, if you still face issues locating them, take the help of the user manual that came along.
2. Disconnect the Power Button
Once you track down the switch headers, check if they have a connection to the power button on your PC case. Usually, there are cables between them. Remove the wiring to disconnect them altogether.
3. Check the PSU Connections
Make sure your PSU is up and running, with the necessary power cables connected. In other words, the 24-pin motherboard and the 4/8 CPU power cables must remain connected.
4. Use a Screwdriver to Turn the System On
Finally, grab a metal screwdriver and touch its tip gently with the pins on the power switch headers. And if all the connections between the components are okay, your PC will turn on.
At this point, you can rest assured that no critical internal failures took place, leaving the doubt on the casing only. So, it is most likely the power button on your computer case that has gone bad.
Nevertheless, there is a temporary fix, assuming that you cannot replace the case immediately. It includes reprogramming the reset button on the casing to work as a power button instead. Doing so is pretty easy as all you have to do is replace the cables on the reset button headers with that on the power button. Unfortunately, you will have to contact the case manufacturer to get a more lasting solution.
Will Motherboard Lights Turn On Without CPU
In most cases, no. Motherboard lights are usually programmed to turn on once it ensures all components are present. However, there can be exceptions, for some motherboards also feature error detection lights.
If your PC won’t turn on, but the motherboard light is on, the above troubleshooting methods should get you somewhere. Yet, if none stated here works, chances are your CPU, PSU, or the motherboard itself is flawed. If you have spare parts, you can try swapping them one by one to specify the error.