You quite likely will need to do nothing. The version 1.20 BIOS was the second version released, in 8/1/2012, one week after the first version, 1.10, dated 7/25/2012. After version 1.20, there are nine BIOS updates. I've never owned a board that had the initial BIOS version on it, and I doubt many if any boards are shipped with the first BIOS version.
In case you don't know, at the time a board is built, the latest or near latest version of the BIOS will be used on the board. The BIOS chip should have a sticker on it, with the BIOS version number installed on the chip. I have two ASRock Z77 boards that I bought about three months apart, and the newer board had a newer version of the BIOS on it, several versions beyond the older board. Even if your board was produced in late 2012, it would at worst have version 1.40 on it, IMO.
Check all the BIOS versions here: ASRock > X79 Extreme11
If by some horrible luck, your board had version 1.10 on it, you could contact ASRock support, and they can ship you a new BIOS chip (which just plugs in by hand, no soldering) with a newer version of the BIOS. You might not even need to pay for it, given your circumstances.