Hello. Well yeterday my comp shut down while i wansnt at it. I tried to turn it back on but it wont start. The Green Light on my motherboad is on so its getting power but when i press the power button on front it wont boot. I dont know whats wrong. Can someone help? Thanks

Does it do nothing at all when you attempt to turn it on? No fans, lights, etc.?

Make sure the power button plugs are connected properly on the motherboard. You say that the green mb led is on? Perhaps use a multimeter to check the voltages b/c even though the light is on, the psu could be under powering your system. Also, check to make sure the correct voltage (110V/ 220V) is selected on the power supply.

One of the reasons that this could be is the Motherboard battery. It normally comes without warning. Lights on your motherboard could still be on, however it will not boot or even post.

I would recommend before you even change your power supply unit, try the Motherboard battery. Take it out and leave it out for 24 hours. If that still does not work try replacing it. They cost about 10 bucks. Sometimes the symptoms for the motherboard battery is that your Operating system begins to loose time, however it is not always the case.

If you do not have any beeping when you start the system try this first. It more likly a battery issue then a loose powersupply cable.