How do I reset the BIOS to default settings on the MAG B550 Tomahawk?

You can reset the BIOS by going into BIOS and pressing F6 to load optimized defaults, or by shorting the JBAT1 Clear CMOS jumper on the motherboard. To use the jumper method, power off the computer, unplug the power cord, short JBAT1 for about 5-10 seconds, remove the jumper cap, then plug in and power on the computer. Make sure the computer is off before clearing CMOS data. (Page 25, 34)