Problem with brand new build

[Dizzysquirrl]

So I'm currently building a computer for my buddy, and when I finally pressed the power button the cpu, gpu, and case fans all spun up, and the lights on the mobo came on. However, it didn't post and I didn't get any sort of beep. I've been troubleshooting for about 3 hours now and cannot figure out what the hell the problem is. I've checked all cables, switched around and removed ram to see if that was the problem, hooked up another verified working PSU only to have the same problem. At this point I'm lost. I even went as far as to remove the mobo battery and reset CMOS, to no avail. Another thing is that happens frequently is all the fans will spin for 1 or 2 seconds when I press power before turning back off, and I have to press the button once to ten times to get it to actually stay spinning. I've narrowed it down to not being the GPU, PSU, pretty sure it isn't RAM or my processor, and both my HDDs are fine, meaning that it has to be my motherboard. However, I wanted to make sure by posting this thread.

Specs:
Mobo: Gigabyte GA z170-UD5
Processor: Intel i5 6500
Ram: G.SKILL Ripjaws V (2 x 4GB) 288-Pin DDR4 3200 (PC4 25600) Intel Z170 Platform
PSU: SeaSonic m12ii 620w Fully Modular
HDD: WD blue 1tb
SSD: Corsair Force 120gb

Any help is appreciated, again this is a buddy's build and I really don't want to disappoint him by saying he'll have to RMA or buy new parts, so if you even think about suggesting something shoot for the stars because it could work.

 

[smorizio]

pull the gpu and one ram stick see if it posts. make sure try pnboard video. if your using an after market heat sink like the evo 212 make sure it not down to tight and is bending the cpu. try the mb outside the case on a box t osee if it shorted out.

 

[Shaun o]

Hi Dizzy,

Just have a check of the cmos jumper and reset pins.
Open is normal mode and bridging of the two pins is clear cmos.

If the board posts for a second or two then shuts down it`s worth a check to see if the bios clear and reset pins are in the right mode as it will exhibit the symptoms you are describing if the two pins are bridged by the jumper.

Silly as it may sound it can be a simple case of that.
Open is normal operation of the bios.