Don't listen to Vojin. Yes, your motherboard MIGHT be defect, but that is probably not it. It happened to me before on a new motherboard in BIOS when i was changing simple things, and I solved it by taking out the CMOS battery (round battery in the middle of the mobo) for 10-15 minutes and putting it back in. (ofc do all this when everything is unplugged). This will hard reset your motherboard to factory settings.
Best of luck