When a desktop computer doesn’t start, there could be a variety of reasons. If the power indicator light is on but nothing appears on the screen then it could be due to failed motherboard. How can you check whether your motherboard has gone bad?
Solution For Motherboard
Use a multimeter to measure the voltage output from some specific pins on the motherboard and that should help in checking if the system is booting properly or not. You don’t need to touch any of these pins manually for this purpose (which might damage your system) as all motherboards have provisions for this test, which can be accessed with screwdrivers. The best way to proceed would be to check what happens when you plug in an external video card into your computer through your PCI slot. It should work, else there is a problem with your motherboard. In that case, you will need to replace it.
Steps for How to Check Motherboard’s Fault
Here are the steps on how to check if your motherboard is working or not:
Plug in an external video card into the system (if available) through a PCI slot and put back the screws in place. Now start your computer and turn on the monitor. Look for any sign of activity from the video card (a blinking light etc.) If nothing happens then first check if the voltage supply to this port corresponds to the specifications mentioned by its manufacturer i.e., make sure that +12V and GND are available at these pins when power is ON. If still no sign is shown then you can confirm that the motherboard is damaged. Replace it as soon as possible for the system to work properly.
GND stands for ground and +12V is used to get power from the power supply unit (PSU).
As a precautionary measure, you should make sure that all connections are good by checking them with a continuity tester, before taking your system apart. This is no replacement for taking the advice of experts. Let me know if this solves your problem or not via the comments section below.
If you are having any difficulties in accessing specific pins on your motherboard then refer to its user handbook or technical manual available online (use google search) as it provides exact details on how to access these test points within various models of motherboards manufactured by different companies (Intel, Asus, Gigabyte, etc.). I am sure that you will find something useful.
If the motherboard is not damaged but there are problems with other components like processor or RAM then the next thing to do would be to make sure that they are properly seated in their respective positions. Badly seated RAM might cause this problem so check its seating before proceeding further. Any of these two situations can give your system a start as it starts the booting process from an external video card connected to a PCI slot and the remaining components get power supply from PSU indirectly through the motherboard. Here is a diagram showing how the system works: