Troubleshooting computer problems when you're building a system can be tricky; many problems can cause similar symptoms. It's a process of elimination; you rule out potential causes to work your way to the solution. When your computer won't turn on, yet you see the LED light lit on your motherboard, here are the potential causes. If you hear beeping when you try to start your system, reference your motherboard manual; those beeps will tell you the problem.
RAM
Improperly seated RAM will cause your system to not turn on. This is because RAM is integral to your computer's operation. Turn off your system and unplug the power cord, then re-seat your RAM modules. If that doesn't help, try using 1 RAM module at a time. If that doesn't work either, try using a different RAM slot and cycle through each RAM module.
CPU
Reseat your CPU. Make sure no pins are bent and that it's sitting properly in its slot. CPUs lock into the motherboard; if you don't close the latch completely they won't work. You should reapply any thermal paste before you remount the heat sink.
Power Supply
Your power supply unit (PSU) could be dying or faulty. Even though the LED light is lit, that only means there is enough current to power it. The easiest way to test this is to use a different PSU to power your system; if it doesn't work you know it's not the PSU. Or you can use your PSU with another system to see if it can power it successfully.
Motherboard
If all else fails, the problem could be your motherboard. Getting a faulty motherboard is not unheard of; you can generally send it back to the manufacturer or retailer for an exchange. This is typically the last resort; you should only do this if you've exhausted all other options.
Tags: your system, your motherboard, doesn work, potential causes, that doesn