Depends on which bios you are on. If it boots with default settings but doesn't after loading XMP/DOCP profile then you need to set the DRAM VBOOT VOLTAGE to the XMP/DOCP voltage(ie: 1.35v ) in the Digi+ submenu of the Extreme Tweakers menu. If it happens when setting flck then, reduce to auto and look for a different bios. I don't know about which CPU you are trying to run or which bios you are on? But the first suggestion I gave you should get you in the right direction.

If for whatever reason you can't get the PC to boot into Bios, make sure you hit the Clear CMOS button once on the back IO shield. That should help you boot into the bios.