Are you using a wireless keyboard?
If so, see if you can use a PS2 connector
or keyboard with a PS2 connector, then get into the BIOS and set USB to Legacy. This should allow to keyboard to enter the BIOS without being connected to a PS2 port after that.
Had to fuss with this on my first Gigabyte MB.
You might also look to see if a BIOS update is available to address this issue (later on).