Intel® Desktop Board DZ77GA-70K boots in American megatrends bios.
Video: Intel DZGA-70K boot problem - YouTube
Time after time I get this problem. Some times after few hours or day left plugged in it boots with Intel bios... I tried to remove battery, updating bios, setting bios to default. it fixes itself randomly.
Intel I7 3770K
Patriot Intel Extreme Masters Viper 3 Series DDR3 8GB (2x4GB)
OCZ Agility 3 in AHCI mode
Video Intel HD4000
WIN8_x64