I built a new machine a few months ago...which completely died a few days ago. I went through all the normal diagnostics I've been doing for years now and narrowed it down to the motherboard or CPU finally.

The machine would get power, but wouldn't post anything...didn't get to bios...and didn't even give any error beeps. So after trying everything i could think of, last night I started trying things that shouldn't have any effect. The thing that ended up working was taking out the CMOS battery completely (instead of just resetting it) and leaving it out for 10 mins.

After that, things proceeded normally! I'm so glad i didn't have to rip everything out of my machine to RMA the motherboard.