Newly built computer turns off and on by itself

[svt20]

Specs:
CPU: i5-4670k
Motherboard: Gigabyte GA-Z87X-UD4H
Memory: G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-1600 Memory
PSU: HX 750
CPU Cooler: Noctua NH-D14 65.0 CFM
GPU: 760s SLI

Hi everyone, I just recently finished building my pc, and I'm having trouble getting it to work properly. When I press the power switch, it stays on for 15 seconds, then turns off, 5 seconds later it turns on by itself, does this same thing repeatedly, until I press the switch on the PSU. I see a yellow light from the motherboard, when the PSU is on, and a red light also appears when I press the power switch for the computer, I don't know if this means anything.

I just tested my PSU with a case fan and a paper clip, the fan stays on, so this means that my PSU is functional. Is the motherboard causing this or something else? I would greatly appreciate some help with this problem.

 

[grummor]

Maybe you didn't properly plugin your cables that connect the power button from the case to the spot on the motherboard, and mixed it with reset or something else ? I would suggest doing an external build first, and testing it again, that way you can shorten the 2 pins on the motherboard to start your PC, and if it works properly than you're simply not routing cables properly, if it doesn't at least you know its one of your components.

Also it may not be related at all, but i would do a RAM check just in case as well, on top of checking if all the components and fans are spinning.

Lastly, do read your mobo's manual, it will have an explanation of what the lights mean.