How in the heck do we determine what component?

[Jglide1]

This setup we are trying to go for is a dual SLI GTX 780, with an intel i7 4820K we got everything hooked up attempted to turn it on and the two GPUs then flashed and the whole build shut down. The Power supply fan turned on then off, as did all the other fans, the current PSU is a NZXT HALE 90 850W. Do we need a bigger PSU? The Power supply isn't faulty either.

 

[USAFRet]

Process of elimination.

Start with the most basic system possible. 1 RAM stick, 1 GPU, etc . Add parts until it fails.

 

[Jglide1]

Process of elimination.

Start with the most basic system possible. 1 RAM stick, 1 GPU, etc . Add parts until it fails.

I think we boiled it down to the point of the MOBO, and the Power supply. We have the problem of it turning on and then off for a second. In order for us to actually turn it on and off we have to manually switch the power off and then on in the back of the PSU to turn it on for that second. I'm starting to believe it's the motherboard.