OK, I went ahead and looked it up. If you look at the picture linked below you'll see a small black button labeled "CMOS_SW" at the top right of the motherboard near the DIMM slots and the large red power button. That is your BIOS reset switch. http://media.bestofmicro.com/Q/2/387146/original/gigabyte-z87x-ud4h_top.jpg
Your motherboard manual will tell you how but it's going to either be a CMOS jumper near the CR2032 battery or it will be a physical "reset" button on the motherboard.
OK, I went ahead and looked it up. If you look at the picture linked below you'll see a small black button labeled "CMOS_SW" at the top right of the motherboard near the DIMM slots and the large red power button. That is your BIOS reset switch. http://media.bestofmicro.com/Q/2/387146/original/gigabyte-z87x-ud4h_top.jpg