Need help with a build.

Does it beep? Does the Power LED flash? If there's some problem so severe that it can't start up, most boards will emit a series of beep codes, LED flashes, or some such. You have to write down the sequence of beeps or flashes and then look it up in the board's manual to see what the problem is. For example, I had a Lenovo laptop here (at my job) that wouldn't start; it would beep once, pause, beep 3 times, pause, 3 again, pause, 1 beep. Looking that up told me I had faulty RAM.