so it goes like this, I finished my new Ivy Bridge build 3 days ago, with only one mishap. The ram I had was too big for the CPU cooler. doh! so got new ram, and set the cooler last night. everything went smooth. system was up 12 hours temps were all below 25 degrees. But this morning when i tried to shut the pc down it wouldn't go. I hit shut down everything would turn off, but then 3 seconds later it just booted up again. I was pressed for time-had to go to work- so I shut it off from the PSU.
I get home, flip the switch hit ON and bam nothing....
I have the Gigabyte GA-z77x-UD5H. which has a debug led on the board and power switch. which are usually illuminated even when the power state is off. they are not. I have a PSU tester when plugged in to the 24 pin and 12v all those powered thing's come on when engaged. Also it shows all the connector's aka Sata, Molax, PCI-e and cpu 8 pin are all right and good, so i'm thinking Motherboard took a poo?
If, after you disconnected everything and pulled it completely apart and rebuilt it from scratch with just the cpu & cooler, 1 stick of ram, reset bios by pulling the cmos battery for a couple of seconds and you still dont get anything from the motherboard I would have to agree with you. Another thing you can try first is while everything is together unplug the power cord from the wall and plug it back in, with the psu rocker switch in the on position of course, and see if it comes on by itself without pushing any buttons. That's a sure sign of motherboard failure