All power connector plugged in? Did the PC boot before the problem appeared?
Would try a different power supply
remove all RAM. try powering on, does it beep or other LEDs show up? Insert one RAM again and try all slots. If it doesn´t work, try it with one of your other RAM sticks.
the motherboard´s label/model/name can be found near the graphics card slot. Something with "X99" in its name