Computer, you're on notice!

After all the hard work to assemble the proper parts for my new computer, and hours of bench-testing the new setup, I finally assembled everything into my case and began the final assembly. This includes 4-6 hours just for filling, priming, and leak-testing the new watercooling setup. Finally, the moment of truth. I press the power button.
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Nothing

(-->Insert exhaustive and comprehensive list of expletives here<--)

Initially, I submitted an RMA to NewEgg for the motherboard, then I punished it by giving it a time-out and ignoring it for a week and a half. Yesterday I decided to finally prep it for shipping, but I'd better test it one last time before I pay another $15 to ship it back to the mainland - again.

Success, kind of.

Horray in that it is fully-functional. Holy crap in that I have absolutely no idea where to begin in the troubleshooting.

So now it sits for a little longer until I can summon the patience to toy with it again. I'm still limping along on my wife's computer, and praying daily to the great pasta god that this system doesn't go belly-up on me while I'm using it.