Weird Keyboard Problem on New Computer

My computer was recently assembled and everything seems to work fine except the keyboard. When I turn the computer on the motherboard image pops up displaying the various keys you could press such as F12 for boot menu. I am able to press F12 to get to the boot menu, but once I am there the keyboard doesn't work. I've tried it with both my keyboard and my sister's keyboard. Her keyboard will light up, so it's definitely getting power. I've also tried all my USB slots. The keyboard doesn't work if I don't press F12 either, it just goes to the Safe Start/Start Normally screen and I can't move the selection there either. Any help would be appreciated, thank you. Also, just post if additional information is needed.