I have an ASUS P5E3 motherboard, QX6700 CPU, 1200W power supply, Corsair XMS3 1600 RAM and water cooling. Up until 2 weeks ago, it ran like a raped ape. Suddenly, it died and when I turn on the power, it shuts down after 27 seconds. I have all hard drives and the video card disconnected. There is nothing else connected to any PCI or PCIE slots. If I remove the power to the cpu or all of the RAM, it stays powered on. But, if I have the power supply connected for CPU and have even one stick of RAM installed, it dies after 27 seconds. I have tried each of the 4 sticks of RAM in slot B1 and they all have the same result. I have tried slot A1, as well. I have cleared CMOS. I am not sure if this means that all sticks of RAM have gone bad, the motherboard has gone bad, or the power supply is kaput.
The water cooling is not the issue, since it is flowing beautifully.
My suspicion would go against the motherboard based on that but check out the breadboarding I linked to.
I was hoping that wasn't the problem. I am having a hard time finding a decent socket 775 full ATX board anymore. The processor is still super great and I hate to waste it. Those Sandybridges look tasty but, unnecessary for my needs.