Hello! My specs are gigabyte z87x-oc@F6 BIOS, i7-4770k@stock, 2x4GB Kingston DDR3 1333 RAM, Windows 8.1 64bit in UEFI mode, hard drive using GPT. As the title said not always but maybe in a week or so my PC will encounter a boot failure with BIOS post 15 for seconds then reboot then the same code shows again, after several times such reboot loops the system will boot to BIOS reset screen notifying me boot failure due to something about bios configuration incompatible with my hardware, and give 3 choices: Load optimized default then reboot, Load optimized default then boot and Enter BIOS setup. If I chose enter BIOS and just do nothing but boot to OS drive, the system will boot without an error. But next time I boot the error message screen will show up again until I choose Load optimized default. Does anyone here could help me on this pls. Thanks!