Make sure that nothing is grounding out on the bottom of the motherboard, and reset the BIOS to factory default. If all that checks out, do a simple bench build:
> remove the mobo (motherboard) from the case and sit it on a foam pad or cardboard; keep the CPU mounted on it.
>insert one stick of memory in the #1 slot
>connect the power supply to the mobo, then plug in the power supply to the wall outlet.
>connect the keyboard, mouse and video to the monitor, do not connect anything else.
>find the tiny socket on the mobo where the Power switch on the front panel cable plugs in, and cross those two exposed electrodes with a screw driver.
The computer should power up and you should get the POST screen on the monitor. If you do not, and you followed the above instructions accurately, either the power supply is bad or the mobo is bad. If you do not have a power supply tester, try swapping it with a different PS. If the fans spin up and you get the POST screen the power supply is bad. If you still get nothing, probably the mobo is bad.
Link here for more detailed information on the above.
Edited by ranchhand_, 23 July 2016 - 08:49 AM.