Gigabyte Motherboard Not Detecting Keyboard
Solution 1:
I found this post because I too have a Gigabyte motherboard (ga-m59sli-s4) in my desktop PC and was unable to change the boot order and launch a linux live distro.
However, I SOLVED my problem!
I was able to use USB-keyboard in the BIOS setup but most options were locked and couldn't be changed (including "USB Keyboard support" which was disabled). The solution was simply to put the keyboard in a different USB-port on the back of the computer; front panel ports didn't work. Assuming you're looking straight at the back of the computer with the motherboard fitted vertically to the left side of the tower, it's the top right USB-port in my case but try them all. Doing this not only unlocked the "USB keyboard support"-option but also enabled all other options in the bios (e.g. set supervisor password, adjust CPU clock speed, temperature control etc.)