I tried a few things once I got home. First, I disconnected most everything from the motherboard as Viking2002 recommended, and then pulled out all but one of the ram sticks. Rebooted it. Fans came on, no beep, but it did not turn off again.
I then went to bed. I will mess with this later.
Remember, I said one
bank - some boards won't boot with just a single stick nowadays. If you look close, they'll be labeled DIMM 0, DIMM 1, DIMM 2, DIMM 3, etc. And they're color-coded, generally black/white or blue/white - you'll find that DIMM 0 and DIMM 2 compose the first accessed bank of memory, so make sure they're both populated. Again, your mileage may vary, depending on the manufacturer. Be sure to read the install guide cover to cover - there are always little quirks that manufacturers engineer into their hardware to distinguish themselves from the guy down the block.
Now, having spouted all that gibberish, there's a damn good possibility that you just got a bad board right out of the box. It's happened to me more than once. I'd check and see what sort of consumer geek rating that model has - there are quite a few that spec out nicely and look good on a web page, but aren't worth the cost of the shipping to send them. Give it one more shot - if it still won't boot, return it and get a different brand.
