Maybe the MB has problem, maybe something else, like the PSU.
Test the PSU by paper clip method.
http://forum.corsair.com/v3/showthread.php?t=63991 if the PSU is fine.
Then try remove all the storages ( HDD/SSD), GPU, and RAM, use onboard iGPU if the PC has, clear the COMS, then boot the PC to see it can boot or not. If the PC does not have iGPU, try other GPU, or test the GPU in other PC.
If the PC can't boot without the boot device, RAM. And either the CPU or MB has problem, but usually the MB will be the one has problem.