When I turn it on all the fans come on, the keyboard lights up momentarily and the CD lights up as the first boot device. But then nothing else happens. When it was working, the next thing that would happen is the keyboard would light up again and the monitor would come on. This no longer happens. I already changed the power supply and even tried removing one stick of memory at a time to eliminate a bad memory problem. The SATA hard drive is spinning so it maybe O.K. Since the bootup sequence doesn't get past checking the CD drive I suspect the Motherboard is not communicating with the hard drive.
Put the motherboard on a piece of cardboard. Put the CPU in, also the beeper and connect the power. Listen for beeps. No beeps may be a bad motherboard.
Add memory. Listen for beeps. Add the video. Listen for beeps and look for video.
I had a similar problem with this board.
Eventually I found that for some reason there was a fault in the internal USB connector.
When I removed both USB connectors from the board it started up fine.
You can see as soon as you plug onto either USB connector the green light on the actual board dims - that was the clue!