Hey, Dumbo74, if my memory serves me correct, you have onboard video. With onboard video you do eliminate the question of bad video card or motherboard. That being said, the very first thing you should get when you power on a system for the first time (I always call it my "smoke" test) is the Motherboard Logo and then comes the Post, then the options across the bottom of the screen.
But you are not getting beyond the power on of the monitor. If you are not seeing the ASUS power-on screen, then you are not getting video, which leads to the conclusion of a dead MB, or a bad Power Supply. Whether you have any devices or not, the MB should go through the check routine and inform you that there is no boot device.
If you have already made arrangements to return the board, then go ahead and do so. If the board fails their inspection they will inform you and send you a replacement. If it passes their test, you will inform you of that and probably send the same board back to you. I have only had one bad mobo in the time I have been building PC's, and fortunately it was not my first. I didn't have the help of the PCW community back then (early 90's). Be as cautious as you can be when removing the CPU, heatsink and fan. Clean the thermal paste off and return them to their original shipping containers (you did keep them right?). Again, do not touch the underside contacts of the CPU.
Remember my friend - adversity builds character. We will get through this, and you will have learned a great deal in the process. In the meantime, have you solved your IDE cable problem, or is that one still out there?