Contact ASRock > Support Request Form telling them what the problems is and ask them to send you an updated bios chip that will work with your cpu. I've read in several threads where they provided the bios chip for free.
An alternative is to buy the cheapest Sandy Bridge cpu, and use it to flash your bios to the most recent version. You could then sell the SB cpu for close to what you paid for it. It will probably cost you a lot more if you pay a local computer shop to update your bios.